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|---|---|---|---|
Making a product that sells without a hassle
I'm planning to make an electronic toy for kids. I was wondering if I'm allowed to sell it if I decide to mass produce.
I'm guessing electronics goes under some kind of safety license. The voltage should be max. 12V but I'd like to use a transformer that connects to the standard plug (110V). With this, there might be some safety consequences.
I will probably ask some company to mass produce. Who will take the liability in case something happens to people? What are my chance to sell my product legally and under the seller protection? Is there too much bureaucracy and I should just forget it or is there some good and easy way to proceed?
I've done some research but haven't found much. This is the reason why I posted here. I'm in the USA. Ok, I also discovered this.
The cost of the certifications are in tens of thousands. That is very discouraging. So my question now would be: Will Intertec cover all of my certification under the US law? | You could start by looking for toy safety legislation. A good starting point is wikipedia: <
Then you can look into the whole issue of manufacturing an idea into a product: <
Then you can take a look into liability: <
All three links of fantastic content were found by using the first result of a Bing search. You can do similar searches for product funding, product development, design inspirations etc. The internet is mankinds most incredible source of virtually all and any information.
Should you go ahead and have further questions, you can post them here, or over at <
Hope that helps. If you have an idea, follow it through. The world is waiting... | stackexchange-freelancing | {
"answer_score": 1,
"question_score": 2,
"tags": "business plan, project"
} |
Different Express JS Installations
I am just getting started with Express Js. Can someone explain the difference between
npm install
and
npm install -g express
(Installation code taken from enter link description here | The `-g` flag means install Express in your global node_modules directory. This enables you to call the `express` command anywhere. `npm install express` would be used to install the `express` library in your app, that is, you would navigate to your app directory and type `npm install express`.
I recommend that you do the following:
`npm install -g express`
Then when you navigate to your app directory, you'd type `npm link express`. This symlinks to the global express install.
Does this help? | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": -1,
"tags": "node.js, express"
} |
Cast binary to enum in python for redis conversion
I am storing an enum in redis. When I load it, the value is in binary. Howe can I cast it to be a python enum?
Example code:
class Position(Enum):
LEFT = 10
RIGHT = 11
current_position = Position.LEFT
r.set('current_position', Position.LEFT)
loaded_current_position = r.get('current_position_side')
print(current_position) # Position.LEFT
print(loaded_current_position) # b'Position.LEFT'
In this example, I'd like to get `loaded_current_position` to equal `Position.LEFT` not `b'Position.LEFT'` | What's being stored is the name of the Enum member. There may be a redis specific answer, but in general you can mix your Enum with another data type, such as `int`, and then cast it back to an Enum upon retrieval; something like:
class Position(int, Enum):
LEFT = 10
RIGHT = 11
current_position = Position.LEFT
r.set('current_position', Position.LEFT)
loaded_current_position = Position(r.get('current_position_side'))
print(current_position) # Position.LEFT
print(loaded_current_position) # Position.LEFT
Note: for the above to work, redis must save and return an `int` | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "python, enums, redis"
} |
TCP Connection: What happens if client does not ACK server FIN
_To explain my question I tried doodling the scenario. Keep in mind I've been digging into TCP on my own so the diagram might not be too reliable. Please let me know if this is so._
**Question** :
What happens if a client that has an open connection with a server over TCP does not ACK a FIN sent by the server (seen at #1)?
**Possible Answers** :
* Does the server close the connection anyway?
* Does the server wait for ACK until connections are cleaned up forcefully?
* If the client wants to keep the connection open after the server sent FIN can the client do anything to tell the server to keep it open? ie Ask for some more data
![enter image description here]( | The FIN will be sent again, exactly as for a data segment, subject to the same retry counters and timeouts.
> If the client wants to keep the connection open after the server sent FIN can the client do anything to tell the server to keep it open? i.e. Ask for some more data.
No. Once a host has sent a FIN it cannot send any more data. However the peer can send in the other direction, unless the host has actually closed the socket. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "tcp, server, client, protocols, tcpclient"
} |
How to lock Orientation for a particular screen in ios in react native?
I want to lock the orientation of my camera screen.
<Stack.Screen name="Camera" component={Camera} options={{ headerShown:false,orientation:'landscape'}}/>
This works fine in android but does not work on ios devices. Is there a way to solve this problem? | You can use below plugin for that <
Set up plugin and configure as mention in their doc and in react native side add below code which you want to Lock Screen portrait or landscape
import Orientation from 'react-native-orientation-locker';
useEffect(()=>{
Orientation.lockToPortrait(); //this will lock the view to Portrait
Orientation.lockToLandscape(); //this will lock the view to Landscape
})
**EDIT**
One more plugin is there you can set screen wise orientation < In my one of the project this is also working . Hope your issue will be resolve on this. | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 2,
"tags": "react native, orientation, landscape, landscape portrait, portrait"
} |
Projection of a closed set in $\mathbb{R}^2$ to one of the factors need not be closed.
$\def\R{{\mathbb R}}$ May I please receive help with the following problem? It is from Munkrees Topology Textbook.
We know the projection to $X$ or $Y$ of an open subset of $X\times Y$ with the product topology is necessarily an open set.
(ii) Prove $X$ and $Y$ are compact topological spaces, then the projection of a closed set of $X\times Y$ to $Y$ is a closed set.
$\textbf{Solution:}$ If $\mu \subseteq X \times Y$ is closed, it must also be compact because closed sets in compact spaces are compact. Being the image of a compact set, $p(\mu)$ is compact. Because $p(\mu) \subseteq Y$ is Hausdorff, and compact sets of Hausdorff spaces are closed, $p(\mu)$ must be closed. | As others in the comments have said, your example for _i._ is good. I'd just be careful when you say
> $A$ is closed, and $p_2(A) = \mathbb{R} \setminus \\{0\\}$ **is open (not closed)**
This could be construed to mean that _because_ $p_2(A)$ is open, it is not closed. It's possible for sets to be both open and closed, so you may want to re-write it (this is very nitpicky).
* * *
Your proof of _ii._ is good, if a bit unclear. Because you say you're not sure about it, I'll spell it out in more detail with links to relevant theorems.
If $\mu \subseteq X \times Y$ is closed, it must also be compact, because closed sets in compact spaces are compact. Being the image of a compact set, $p(\mu)$ is compact. Because $p(\mu) \subseteq Y$ is hausdorff, and compact sets of hausdorff spaces are closed, $p(\mu)$ must be closed. | stackexchange-math | {
"answer_score": 3,
"question_score": 1,
"tags": "general topology, metric spaces, compactness, product space"
} |
Example of independent and identically distributed random variables
Consider the probability space $(\Bbb [0, 1], \mathcal{B}, \mu),$ where $\mathcal{B}$ denotes the Borel sigma algebra in $[0, 1],$ and $\mu$ is the standard Lebesgue measure restricted to $[0, 1]$. Could you please provide an example (mathematically defined) of two absolutely continuous random variables $X_1, X_2 : ([0, 1], \mathcal{B}, \mu) \rightarrow \Bbb R$ that are independent and identically distributed? | Let, for all $x \in [0,1]$, $X_1(x) := \sum^{\infty}_{n=1} \lfloor \frac{x}{2^{2n}} \rfloor \frac{1}{2^n}$ and $X_2(x) := \sum^{\infty}_{n=1} \lfloor \frac{x}{2^{2n-1}}\rfloor \frac{1}{2^n}$.
I leave you, as an exercise, to prove that $X_1$ and $X_2$ are indeed iid.
Hints:
1. For every $k \in \mathbb{N}$, and $n \in \mathbb{N}^*$, compute $X^{-1}_1([\frac{k}{2^n},\frac{k+1}{2^n}))$ and $X^{-1}_2([\frac{k}{2^n},\frac{k+1}{2^n}))$. Each of these should be a dyadic interval.
2. Deduce from this that $X_1$ and $X_2$ are both uniform and independent. | stackexchange-math | {
"answer_score": 3,
"question_score": 2,
"tags": "probability theory, measure theory, random variables, independence"
} |
Dynamic parameters on dynamic (complex) query JPA/Hibernate
I am trying to build a complex query that involves filtering which i did it like so on JDBC:
private String buildFilteredQuery(List<Long> extensions, List<Long> categories, Long courseId) {
...
StringBuilder extensionQuery = new StringBuilder();
if (!extensions.isEmpty()) {
extensionQuery.append("AND (");
extensions.forEach(e -> extensionQuery.append("fileExtensionId = ? OR "));
extensionQuery.delete(extensionQuery.length() - 4, extensionQuery.length());
extensionQuery.append(")");
}
...
}
The problem is that now over JPA i can't really do this since instead of the ? i should put the variable to be mapped (e.g **:fileExtension** )
So how can i build a dynamic query that takes dynamic parameters to it? | Like @Guillaume said, i ended up only using one stament with an IN clause:
private String buildFilteredQuery(List<Long> extensions, List<Long> categories, Long courseId) {
...
StringBuilder query = new StringBuilder();
if (!extensions.isEmpty()) query.append("AND ( fileExtensionId IN ( :extensionIds ) ) ");
...
} | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": -1,
"tags": "database, hibernate, spring mvc, jpa"
} |
git --amend --no-edit rejected push
Today I discovered the `--no-edit` for the `--amend`. However, it leads me to the following problem. Here the steps:
* git clone
* did some changes to the code
* git add .
* git commit --amend --no-edit
* git push origin master
! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to '
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
Why?
Note: I'm the only one which works on that repo. | Amending the last commit rewrites history. If that's what you want to do, you can do that with `git push --force`.
The reason it tells you you're behind is because the last commit that exists both locally and remotely (aka "merge base") is the tip's parent. In that regard, you're one commit behind the remote, which already has a commit on top of the aforementioned merge base. | stackexchange-stackoverflow | {
"answer_score": 9,
"question_score": 2,
"tags": "git, push, git amend"
} |
What's a clean way to sort a hash in Ruby without returning an array of key-value pair arrays?
When I sort a hash in Ruby it returns an array of key-value pair arrays.
I would like it to return a hash.
What's a clean way to do this? inject? | Hashes aren't really sortable objects. Since Ruby 1.9, they maintain keys in the order in which they were added, which is convenient, but in terms of the data structure, order is not relevant.
You can test this by comparing `{ a: 1, b: 2 } == { b: 2, a: 1 } #=> true`. The same is not true for arrays, in which the order is an important feature.
You'll find many methods in Ruby actually convert hashes to enumerables, which are closer to arrays in that they have a defined order. When returning a value from something like `sort`, you get an array.
You can easily convert it back into a hash using `Hash[...]`:
Hash[hash.sort(...)] | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "ruby, sorting, hash, inject"
} |
In Python, how can I create lists that contain a certain index of other lists?
Say I have several lists
A = [1,2,3]
B = [4,5,6]
C = [7,8,9]
How can I create new lists so that they contain matching indexes, as in:
D = [1,4,7]
E = [2,5,8]
F = [3,6,9]
The original lists will always contain the same number of elements, and I need this to work for any number of elements and any number of lists, not just three. I figure I need to loop over a range, but I'm not sure how to go about it. | If I understand you correctly, you may be looking for zip():
>>> a = [1, 2, 3]
>>> b = [4, 5, 6]
>>> c = [7, 8, 9]
>>> zipped = zip(a, b, c)
>>> zipped
[(1, 4, 7), (2, 5, 8), (3, 6, 9)]
If instead of several lists, you have a list of the lists that you want to zip, then you can use `*` for unpacking the sublists, as follows:
>>> myListOfLists = [[1,2,3],[4,5,6],[7,8,9]]
>>> zipped = zip(*myListOfLists)
>>> zipped
[(1, 4, 7), (2, 5, 8), (3, 6, 9)] | stackexchange-stackoverflow | {
"answer_score": 6,
"question_score": 0,
"tags": "python, list"
} |
(bxslider) Using the slider pager with words instead of circles
Is there a way to replace the circles in a pager for a slider with a word that represents each slide (like a clickable menu that slides the content below it)? The options are here < but not sure which one could accomplish this? | Use buildPager:
> If supplied, function is called on every slide element, and the returned value is used as the pager item markup.
Example page is here:
Your code would look something like this:
$('.bxslider').bxSlider({
buildPager: function(slideIndex){
switch(slideIndex){
case 0:
return '<div>First slide</div>';
case 1:
return '<div>Secoond slide</div>';
case 2:
return '<div>Third slide</div>';
}
}
}); | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 0,
"tags": "javascript, jquery, slider, bxslider, jquery ui slider"
} |
Conky disappearing when I show desktop
I'm using Ubuntu 16.04 and when I press `Ctrl`+`Super`+`D` to show up my desktop, conky disappears. | This works for me with the Cinnamon desktop environment. (Linux Mint 18 - Which is essentially Ubuntu 16.04)
In my conky config:
own_window_class Conky
own_window yes
own_window_type dock
If that doesn't work in Unity (what comes with Ubuntu, try this)
own_window yes
own_window_type normal
or
own_window no
own_window_type desktop
Source: How to fix: conky disappears after click on desktop or other window? | stackexchange-askubuntu | {
"answer_score": 5,
"question_score": 2,
"tags": "16.04, conky"
} |
What it the difference between kubernetes and azure Devops in terms of CI/CD
I am not sure the comparison of these two. we are using Azure Devops for the CI / CD operation as a part of the project implementation. I have heard about the kubernetes . Is it same as the Azure Devops CI /CD . My question is is the CI / CD can achieved using kubernetes as well ? If we have Azure Devops then we do not need kubernetes ? | Azure DevOps is not the same as Kubernetes. Azure DevOps is used mostly for build your application and deploy them for example on Kubernetes or some Web App. Using Kubernetes you can run application in container, so running CI/CD in Kubernetes is possible when you run build process in containers but i'm not sure if it is worth the effort when you already using Azure DevOps.
In short:
* Azure DevOps - build and deploy you application
* Kubernetes - running your application (that could be deployed using Azure DevOps) | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 0,
"tags": "git, kubernetes, azure devops, continuous integration, continuous delivery"
} |
Is this function $f(x f(x)+y)=x^{2}+f(y)$ onto ??
**question** \-
Is this function $f(x f(x)+y)=x^{2}+f(y)$ onto $\mathbb R\to\mathbb R$?
I just need to know that is this function is onto or not ... by putting $y=0$ and $f(0)=s$ , I get $f(x f(x))=x^2 + s$ but i am not able to find an x such that $f(x)=y$ ...
any help will be appreciated
thankyou | With $a:=f(1)$, we have $$ f(a+y)=1+f(y)$$ hence by induction $$\tag1 f(na+y)=n+f(y)$$ for all $n\in\Bbb N$, and by letting $y\leftarrow y-na$ also $$ f(y)=n+f(y-na)$$ i.e., $(1)$ holds for all $n\in\Bbb Z$. In particular, $$ f(na)=n+f(0)\qquad\text{for }n\in\Bbb Z.$$ Given $z\in \Bbb R$, let $n=\lfloor z-f(0)\rfloor$ and $y=na$ so that $f(y)\le z$. Now let $x=\sqrt {z-f(y)}$ to find $$ f(xf(x)+y)=x^2+f(y)=z.$$ | stackexchange-math | {
"answer_score": 3,
"question_score": 1,
"tags": "functions, functional equations"
} |
SQL count hour for each date of a datetime column
I have a subquery which returns just one column with a datetime type:
LOG_DATE
---------------------
2014-06-30 08:15:00
2014-07-01 08:00:00
2014-07-01 08:45:00
2014-07-01 10:00:00
2014-07-01 13:00:00
2014-07-01 14:00:00
2014-07-01 14:30:00
2014-07-01 14:55:00
2014-07-02 08:10:00
2014-07-02 09:00:00
2014-07-02 09:10:00
2014-07-02 09:25:00
2014-07-02 09:40:00
2014-07-02 10:10:00
I'm trying to write a script using this subquery which should return:
DATE | HOUR | TOTAL
----------------------------------
2014-06-30 | 08:00:00 | 1
2014-07-01 | 08:00:00 | 2
2014-07-01 | 10:00:00 | 1
2014-07-01 | 13:00:00 | 1
2014-07-01 | 14:00:00 | 3
2014-07-02 | 08:00:00 | 1
2014-07-02 | 09:00:00 | 4
2014-07-02 | 10:00:00 | 1
Can someone help me how to get it? | This should get you started:
SELECT CONVERT(VARCHAR(10), LOG_DATE, 120), CONVERT(VARCHAR(2), LOG_DATE, 108)+':00:00', COUNT(*)
FROM TABLE1
GROUP BY CONVERT(VARCHAR(10), LOG_DATE, 120), CONVERT(VARCHAR(2), LOG_DATE, 108)+':00:00'
ORDER BY CONVERT(VARCHAR(10), LOG_DATE, 120), CONVERT(VARCHAR(2), LOG_DATE, 108)+':00:00' | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "sql, sql server"
} |
Let the bottom div fill the rest of the page
I have the following structure: image
I don't know the height of the head but I want the second container to fill the rest of the height.
I found some solutions when I would now the size of the head but I don't. I want that the upper container is fitting to its content while the second container is filling the rest of the window.
How to solve this? | You can use JavaScript/jQuery
var topDivHeight = $("#topdiv").height(),
totalHeight = $(document).height();
$('#bottomDiv').height(totalHeight - topDivHeight ); | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "html, css"
} |
Linq Puzzle: How do I convert this foreach to linq syntax?
List<string> nameSpaceSuffixes = GetSuffixes();
foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
{
foreach(var suffix in nameSpaceSuffixes)
{
if (assembly.GetName().Name.EndsWith(suffix))
Register(container, assembly, suffix);
}
} | As a query expression:
var query = from assembly in AppDomain.CurrentDomain.GetAssemblies()
from suffix in namespaceSuffixes
where assembly.GetName().Name.EndsWith(suffix)
select new { assembly, suffix };
foreach (var result in query)
{
Register(container, result.assembly, result.suffix);
}
I haven't gone down Ani's route of using `List<T>.ForEach` \- I personally prefer to use a normal `foreach` statement. LINQ is great for the declarative querying; `foreach` is godo for the imperative action taken on each element.
Note that my query expression is almost equivalent to Ani's dot notation; the C# compiler would use a slightly different overload of `SelectMany`, that's all. In _this_ particular case I think the query expression is easier to understand; in simpler cases I prefer dot notation. | stackexchange-stackoverflow | {
"answer_score": 6,
"question_score": 2,
"tags": "c#, linq, foreach, linq to objects"
} |
Tab order VSTO Excel
I'm looking through some VSTO excel code and there seems to be a major wheel reinvention swtich statement in an event handler which is attached to every control (text boxes, combos etc), calling Focus() depending on the Tag property (being used in place of a tabIndex property)
Is tab order alien to VSTO? | The controls are sitting on an Excel worksheet, and are placed relative to cells.
Cells are the main point of interaction with Excel, rather than the controls.
However, if you only want users to use the controls, you can lock the cells using Protection, and only allow them access to the Controls.
Effectively, you are stopping them tabbing on the cells, so would only have access to your controls.
Note: I'm not recommending you do this, but, if it meets your requirements...... | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "excel, vsto, tab ordering"
} |
Google Maps v3 AutoComplete get the Suggestions
I am trying to use autocomplete in Google Maps. I am getting the results. but i want to college the results and feed it to my themes Autocomplete Plugin to make it look better. I am not able to get the list of the places as a modifiable variable array.
var zoomLevel = 13;
var lat = 13.00487;
var lng = 77.576729;
var mapOptions = {
center: new google.maps.LatLng(lat, lng),
zoom: zoomLevel,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
var map = new google.maps.Map(document.getElementById('map'), mapOptions);
var input = document.getElementById('search-google-places');
var options = {
types: ['geocode']
};
var autocomplete = new google.maps.places.Autocomplete(input, options);
var place = autocomplete.getPlace();
console.log(place); | Request the **autocompleteService** directly instead of using a places.Autocomplete, the response will give you the predictions. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "google maps api 3, autocomplete"
} |
Showing numpy array as image with animation
I have a 2D numpy array which I want to show as an image. Now using matplotlib `plt.imshow(my_array)` works fine. The problem is that my array keeps on changing. There is a function `foo()` which changes the array. I want to show that array as image and also the changes done by foo function. It should be only one image window and the updates are done in that window instead of creating new one. `FuncAnimation` is one way but it is used with plots. How can I use it to show image?
My image is actually an arena of obstacles. I am trying to show path finding and visualise it. Breadth-First Search and Dijkstra's algorithm I am trying to visualise.
Kindly help. Thank you. | Not knowing how your code is structured but one solution to your problem could be using `plt.pause()`
An example,
import numpy as np
from matplotlib import pyplot as plt
def draw_me(img):
plt.pause(.01)
plt.imshow(img)
for idx in range(12):
img = np.random.randint(0, 255, (12,12))
draw_me(img)
**note** if you are using Sypder make sure you're not inline ploting in the console. For me that means entering the following in the console,
%matplotlib auto
%matplotlib qt | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 1,
"tags": "python, numpy, matplotlib"
} |
Does Rails :delegate method always load the association?
I'm using the :delegate method in Rails 3.2 to get/set methods on an object's association. This seems to **always** load the association, even when I'm not calling the delegated methods.
For instance, if I've got:
class Post < ActiveRecord::Base
delegate :name, :to => :author, :prefix => true
end
If I do `Post.all.limit(10)` ActiveRecord also loads the author for each of those posts, regardless of whether I'm ever accessing `@post.author_name`.
Is there a way to load delegated associations lazily? Or am I better off writing custom wrapper methods, which will load associations lazily? | They don't eager-load for me, could it be something else in your code?
In any case I've never liked using `delegate` with `prefix`, it seems kind of odd. You're no longer actually delegating a method, you've just defined a new method in a difficult to read and parse way. I'd just write a wrapper method as you suggested. | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 1,
"tags": "ruby on rails, ruby on rails 3, activerecord"
} |
how Generate QR Code with complex data like contact information?
Now I generate QR Code with simple text and for that I use below demo project.
IOS_QR_Code_Generator
And for generating QR code:
NSString *code = @"JAY RAPARKA SIMPLE Encoding string";
Barcode *barcode = [[Barcode alloc] init];
self.view.backgroundColor = [UIColor whiteColor];
[barcode setupQRCode:code];
ivQRCode.image = barcode.qRBarcode;
Right now I just encode **"JAY RAPARKA SIMPLE Encoding string"** this simple text but I want to generate QR code for more complex data like (Contect information, link/URL, account balance on the base of id,etc..). So please any one done this earlier than please help me.
Thank you!
For decoding I use ZBar sdk and it also works properly and encoding also work but I just want to generate QR for more data. | You can create contact information by giving text in bellow format
BEGIN:VCARD
VERSION:2.1
N:;Company Name
FN:Company Name
ORG:Company Name
TEL;WORK;VOICE;PREF:+16045551212
TEL;WORK;FAX:+16045551213
ADR;WORK;POSTAL;PARCEL;DOM;PREF:;;123 main street;vancouver;bc;v0v0v0;canada
EMAIL;INTERNET;PREF:[email protected]
URL;WORK;PREF:
NOTE:
CATEGORIES:BUSINESS,WORK
UID:A64440FC-6545-11E0-B7A1-3214E0D72085
REV:20110412165200
END:VCARD | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 0,
"tags": "ios, iphone, qr code"
} |
Is it possible to use GraphQL with Twirp RPC framework by Twitch
I have a Golang program working with Twirp and I want to create GraphQl server, but as far as I know, twirp build on top of the Rest API | # It is definitely possible.
You Just have to make a wrapper over the Twirp based RPC API.
This is a similar case to wrapping a GraphQL API over a Rest API.
You should also read this article, where the wrapping of a graphql api over a rest one is shown. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "go, graphql, twirp"
} |
Environment variable is not set MacOS
I need to set environment variables to build an Ionic application, open the terminal and run the command:
export ANDROID_SDK_ROOT=$HOME/Android/Sdk
Without closing the terminal I type echo $ANDROID_SDK_ROOT, and the environment variable is returned perfectly, so I run "source ~/.bash_profile", to update the environment variables. I open and close the terminal and my environment variable is empty! I tried to set it manually by opening the environment variables files, with a text editor but without success. | For macOS 10.15 Catalina and Newer, you need to use a `.zshenv` file instead of `.bash_profile`. This is because, by default since Catalina, the terminal uses `zsh` instead of bash.
Export paths permanently in the following manner: Create `.zshenv` file:
touch ~/.zshenv
open -a TextEdit.app ~/.zshenv
Type out the export you want to do in this format:
`export ANDROID_SDK_ROOT=$HOME/Android/Sdk`
and save it. (From this old answer) | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": -2,
"tags": "macos, environment variables, zsh"
} |
Is it OK not to call close method?
Below code is the serialize method of org.springframework.util.SerializationUtils(spring-core.3.2.1.jar). As you can see, there is no oos.close method. Is it OK not to call close method?
!org.springframework.util.SerializationUtils | In this particular case, it's okay - the two streams involved (the `ObjectOutputStream` and `ByteArrayOutputStream`) don't use any unmanaged resources (file handles, network handles) etc so it's okay for the garbage collector to just take care of it.
Personally I usually close even streams like that, just to be in the right habits and in case someone changes the type of the stream to one that _does_ have unmanaged resources, but I don't think it really counts as a _bug_ in this case. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "java io"
} |
how to set up python web dev environment
the set the i have so far is: windows 7 64bit Apache 2.2.14/mysql/php 5.3.1
i installed python 2.7. not configured.
i tried installing mod_python but it kept telling python 2.5 is required | Dump mod_python. It's dead, Jim. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "python, apache"
} |
How to connect Expo with arduino
I want to connect my apps with Arduino which can control the switch through the apps.
However, I found out that expo does not support Bluetooth and I'm trying to use another way by communicating through the serial port which also unsuccessful also because Expo does not support it.
Are there any other ways to connect Expo projects with Arduino? | It is not possible for 2 reasons:
* Arduino doesn't have BT
* Expo is a multi platform mobile SDK. But since iOS has a bad and incomplete BT implementation, Expo will probably not implement it.
You can add a BT module to your Arduino like HC-05 or HM-10. (use HM-10 if you want to connect it with iOS, since iOS is not able to transmit data over the standard SPP - Serial Protocol Profile).
There are some apps on the store to connect a HM-10 devices and switch on/off something: <
Or you can use an ESP32 instead of an Arduino. So you will be able to connect it over WiFi or BT. | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "react native, arduino, expo"
} |
r: object not found when using fourier within a formula within a function
(using the `forecast` package in `r`). if I write:
tslmf <- function(y, h, myK,...) {
fourier(y, myK)
}
I can call it with `tslmf(taylor, h=1, c(1,1))` and everything works. but if I write:
tslmf <- function(y, h, myK,...) {
fit <- tslm(y ~ trend + fourier(y, K=myK))
}
and call it exactly the same, I get: `object 'myK' not found`
AND if I do:
tslmf <- function(y, h, myK,...) {
z <- fourier(y, myK)
fit <- tslm(y ~ trend + z)
}
it does work!
why is that? | `fourier` called inside `tslm` is looking for `myK` in the environments `forcast`, `base` and `global` and there it does not find them. The _enclosing environment_ of `tslm` is NOT the environment of your function, where you have `myK`.
See Function environments, apply() and forceAndCall() ignoring get() from parent.frame() or Accessing variables passed to, or defined in, parent R function. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "r, formula, forecasting, lm"
} |
Beego ORM with MySQL
I am new to Beego as well as Go. I read its documentation but it puts every ORM operation in the main package instead of model package. I can't understand how to organize the code. I am really very confused. | You can feel free to follow steps as below, and try to build your first database program.
1. Build [Models] According to the table structure of your database.
2. Initialize the ORM
3. New an ORM instance
4. Operate CRUD as your want
Link:
Guidance for Beego/orm configuration
<
Guidance for operating CRUD on Beego/orm
< | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 0,
"tags": "go, beego"
} |
Making a loop efficient in Matlab code: use C or will Java do?
I want to speedup some matlab code involving a loop. A common solution is to code the loop in C and call it from matlab. However, I was wondering if I can get similar benefits from implementing the loop in Java instead - perhaps the just-in-time compilation makes it faster? | Before you start working with outside code: Have you pre-allocated your variables? Can you vectorize your loop? While the Matlab just-in-time compiler has become a lot better over the years, there are still cases where vectorization brings significant improvement. Also, note that quite a few Matlab functions (those for which you don't see code when you open them in the editor) are implemented in C or Fortran, so you may not observe a dramatic speed gain.
If you can't speed up your Matlab code by better writing it in Matlab, and if it does look likely that reimplementing might actually bring you any benefit, then C might be fastest, though Java might be not too far behind (again it depends on the code you want to speed up - it might be a good idea if you posted it here). If you're much more familiar with Java than C, I suggest trying to go the Java route. | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 2,
"tags": "java, matlab, mex"
} |
Why does HashMap in java internally use array to store Entry Objects and not an ArrayList?
Why does HashMap in java internally use array to store Entry Objects and not an ArrayList ? | The reason for this is highly likely that `HashMap` needs to control how its internal table is resized according to the number of entries and the given `loadFactor`.
Since `ArrayList` doesn't expose methods to resize its internal array to specific sizes (`HashMap` uses powers of 2 for its size to optimize rehashing, but `ArrayList` multiplies capacity by 1.5), it simply wasn't an option to be considered.
Also, even if `ArrayList` did increase capacity in the same way, relying on this internal detail would tie these two classes together, leaving no room to change the internal implementation of `ArrayList` at a later date as it could break `HashMap` or at the very least make it less memory efficient. | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 1,
"tags": "java, collections, hashmap"
} |
remove all instances of item from the input array rather than just one
public static String[] remove(String[] symbols, String c)
{
for (int i = 0; i < symbols.length; i++)
{
if (symbols[i] == null ? c == null : symbols[i].equals(c))
{
String[] copy = new String[symbols.length-1];System.arraycopy(symbols, 0, copy, 0, i);
System.arraycopy(symbols, i+1, copy, i, symbols.length-i-1);
return copy;
}
}
return symbols;
} | When you remove from the array you do not want `i` to increase. You also do not want to return anything until after the loop.
Replace the line
return copy;
with
symbols = copy;
i--;
The line `return copy;` makes no sense if you want to continue to remove elements. | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": -3,
"tags": "java, arrays, string"
} |
Identify last item in alpine.js for loop
I have a for loop in my alpine.js code
<template x-for="(value, index, collection) in forecastQ4Values" :key="index">
<div class="..."><span x-text="value"></span></div>
</template>
How can I add a class only to the last item in the for loop? Basically I want to hide the last element until some variable changes.
For instance like this, but only on the last item.
<template x-for="(value, index, collection) in forecastQ4Values" :key="index">
<div :class="{ 'invisible': !productDActive }" class="..."><span x-text="value"></span></div>
</template>
Thanks | If you have access to index my first thought would be to check where you are in the loop. Like so:
<template x-for="(value, index, collection) in forecastQ4Values" :key="index">
<div :class="{ 'invisible': (forecastQ4Values.size == index+1) }" class="..."><span x-text="value"></span></div>
</template> | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 0,
"tags": "alpine.js"
} |
How to get old value in OpenDJ server?
I've already enabled changelog on a standalone OpenDJ server and have "cn=changelog" appeared as one of nodes. And my problem is, that after fetching data from "cn=changelog", attribute "changes" contains only new value of changed attribute, without the old one. E.g. when attribute "cn" changed from "Peter" to "Paul", in "changes" there is only "Paul". Is it possible to get also old value of attribute? If yes, could you tell me where should I search for it or how should I configure OpenDJ to obtain it? | Ok, after digging in documentation (Procedure 8.15), I found out that there is possibility to set 'ecl-include' option, which causes that changelog entry contains new attribute - 'includedAttributes'. This attribute includes old values (before entry's modification) for those attributes which we defined in 'ecl-include' option. But the disadvantage is, that 'includedAttributes' contains all defined attributes - regardless if those attributes has changed or not during entry's modification. So, for my question, it should be configured like this:
dsconfig set-external-changelog-domain-prop -h host -p port -D cn="Directory Manager" -w password --set ecl-include:"cn"
From now on, next changelog entries will contain 'includedAttributes' attribute with old 'cn' value, which is 'Peter'. | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "ldap, opendj"
} |
Component requires specific voltage and current but the math doesn't add up
I'm trying to get an old soviet era cathode ray tube working.
On the data sheet it says the heating element needs between 5.7V and 6.9V, and between 0.54A and 0.66A, but I've measured the resistance of the heating element and it reads as 1.5 ohms. If I apply 6V then I would get 4A.
Am I missing something here? Is it possible to limit the current but keep the voltage at 6V?
I really don't want to burn out the heater as it will be impossible to replace. | Many tubes are designed to run on a nominal 6.3V for the heater.
The reason you are reading a very low resistance is that the heater is cold. As it heats up, the resistance increases.
If in doubt, try running it off a bench power supply with a current limit. But allow for a current surge when it's first turned on. | stackexchange-electronics | {
"answer_score": 34,
"question_score": 8,
"tags": "current limiting, ohms law, crt"
} |
Output currency symbols
Is there a way to output the currency symbols for each accepted payment currency in a Craft Commerce site?
Consider the following simplified example;
{% set currencies = craft.commerce.paymentCurrencies %}
{% if currencies|length > 1 %}
<select name="paymentCurrency">
{% for currency in currencies %}
<option>{{ currency.iso }}</option>
{% endfor %}
</select>
{% endif %}
Instead of the currency ISO code being output in the option, I also want to show the symbol. I can't find a method for doing so. | You don't need to create your own symbol map - it exists as a yii translation:
{% set localeData = craft.i18n.getLocaleData() %}
{% set currencyIso = 'USD' %}
{{ localeData.getCurrencySymbol(currencyIso) }} | stackexchange-craftcms | {
"answer_score": 4,
"question_score": 2,
"tags": "plugin craftcommerce, currency"
} |
How to change orientation in tig status view
!enter image description here
I need to swicth between landscape and portrait orientations in **tig** status view cause sometimes diff line doesn't fit to right part of view. | You can change the orientation use the `vertical-split` option. In version 2.0, it is set to `auto` by default, which will use a heuristics to determine whether to use landscape or portrait orientation (note: in the Tig docs this is called _horizontal_ and _vertical_ split).
Following is the option's documentation for version 2.0:
> **vertical-split** _(mixed) [auto|]_
>
> Whether to split the view horizontally or vertically. "auto" (which is the default) means that it will depend on the window dimensions. When true vertical orientation is used, and false sets the orientation to horizontal. | stackexchange-stackoverflow | {
"answer_score": 21,
"question_score": 8,
"tags": "git, tig"
} |
Why is this matrix function smooth?
Let $A$ be a real, invertible, $k \times k$ matrix, let $B$ be a real $k \times (n - k)$ matrix, and let $C$ be a real $(m-k) \times k$ matrix.
How is the function $$ F:(A,B,C) \mapsto CA^{-1}B $$ smooth (i.e. $C^\infty$)? What is the derivative of $F$?
I saw this function in a proof that the set of $m \times n$ matrices with rank $k$ form a submanifold of the set of all $m \times n $ matrices. | Matrix multiplication is obviously smooth, since entries of the product are quadratic polynomials in the entries of the two matrices.
The entries of $A^{-1}$ are rational polynomials of the entries of $A$, which may not be obvious at first but is a consequence of Cramer's rule. Therefore matrix inversion is smooth away from $\det A =0$.
Finally since matrix multiplication is linear, the differential satisfies the product rule: $$dF = dCA^{-1}B - CA^{-1}dAA^{-1}B + CA^{-1}dB$$ where the formula for the differential of $A^{-1}$ can be derived from differentiating both sides of $$A^{-1}A = I.$$ | stackexchange-math | {
"answer_score": 1,
"question_score": 0,
"tags": "derivatives, smooth manifolds"
} |
Invalid macro expansion argument character
I am attempting to compile pooler-cpuminer and when running make I get this error:
sha2-arm.S:190:invalid macro expansion argument character (+)
Any help? I've looked and haven't found a solution yet. | Aha I fixed it. There was a nomacro.pl script I had to run. | stackexchange-superuser | {
"answer_score": -1,
"question_score": 0,
"tags": "ios, make, gcc, arm"
} |
What should be logged in Nodejs?
We are starting out a new Nodejs project, and I am working on wiring up Winston to Loggly.
Since we are new to node, my question is, what is typically information that should be logged and in what format for Loggly to accept it? What do you guys find helpful when going through the logs, i.e, remote address, method where error happend, etc... ? | This Ultimate Guide to Logging in Node give some some good ideas you can use as a starting point. It also gives you tips on how to troubleshoot common problems. I helped put the team together to write it. It's an open source guide, and we take suggestions on topics and content from the community. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "node.js, error logging, loggly"
} |
How to remove foreign security principals from my get-adgroupmember output?
I am trying to pull up some details of group members, but the group is domain local and contain many foreign security principals. Please advise how to ignore them from my output
Get-ADGroup -Filter {GroupScope -eq "DomainLocal"}
-SearchBase "CN=Workstation_LOCAL,OU=Security Groups,OU=Normal Users and Groups,DC=conteso,DC=com" |
Get-ADGroupMember | Get-ADUser -Properties * |
select name, samaccountname, employeenumber, department, emailaddress | You can just use a `Where-Object` clause to filter the results. Since you're piping into `Get-ADUser`, you should filter by users, rather than filtering on "not foreign security principal", since groups can contain any AD object (like computers, contacts, or other groups).
It would look something like this:
Get-ADGroup -Filter {GroupScope -eq "DomainLocal"} -SearchBase "CN=Workstation_LOCAL,OU=Security Groups,OU=Normal Users and Groups,DC=conteso,DC=com" |
Get-ADGroupMember | Where objectClass -eq user | Get-ADUser -Properties * |
Select name, samaccountname, employeenumber, department, emailaddress | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "powershell, active directory"
} |
imshow() produces different output to imwrite()
I was wondering how it is possible to save an image created by imshow() in matlab. The code below uses the imshow() function with the min and max arguments specified - How can I apply this directly to the image itself instead of just specifying Matlab to _show_ it?
imshow(img4fft, [1 300000]);
imwrite(img4fft, 'img.png');
Writing to the file produces a different output to what is shown via imshow().
Can anyone suggest how to get the output from imshow() saved as an image?
Many thanks MatLab is an alien language to me! | I obtain the same result by doing:
img4fft2=min(double(img4fft),300000)/300000;
imwrite(img4fft2,'img.png'); | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 1,
"tags": "matlab, image processing"
} |
How would you test a lexer?
I'm wondering how to effectively test a lexer (tokenizer).
The number of combinations of tokens in a source file can be huge, and the only way I've found is to make a batch of representative source files and expect an specific sequence of tokens for each of them. | Your grammar probably has some rules for each token on how it can be produced (for example, that a `{` signifies a BLOCK_START token, or that a string-literal token is delimited by '"' characters). Start writing tests for those rules and verify that your lexer produces the correct token in each case.
Once you have a test for each single token, you can add a few tests for interesting combinations of tokens. Focus here on token combinations that would reveal an error in your lexer. The token combinations don't have to make sense to a parser for your language, so it is entirely valid to use `+++++12` as input and expect the tokens INCREMENT, INCREMENT, PLUS, INTEGER_LITERAL(12) as output.
And finally, make sure you have some tests for faulty inputs, where the lexer will not be able to recognize a token. And although I mention them last, they certainly don't have to be the last tests you create. You could just as well start with these. | stackexchange-softwareengineering | {
"answer_score": 16,
"question_score": 15,
"tags": "unit testing, testing, parsing, lexer, tokens"
} |
Laravel 5 Migration change length of existed column
It not work, I search so many ways, How can I change length of value in laravel 5
public function up()
{
Schema::table('articles', function (Blueprint $table) {
$table->string('name',50)->change();
});
}
Thank you all for reading! | Regarding documentation, your example should work:
Schema::table('users', function ($table) {
$table->string('name', 50)->change();
});
Just run `php artisan migrate` command to execute it. | stackexchange-stackoverflow | {
"answer_score": 84,
"question_score": 49,
"tags": "laravel"
} |
The formula in this cell refers to a range that has additional numbers adjacent to it
I can turn off this error warning in preferences, but Excel will still not allow me to sum some of these cells: enter image description here
Can't figure out why some rows work and others don't... driving me nuts! Help! | You need to increase the width of column J! ### means the value is too wide to display!
Numbers/dates that have too many digits to display in the given cell get replaced by hashes, but strings overflow or display as much as possible. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "excel"
} |
SQL Server 2008 - boolean variable change query
I have the following query:
DECLARE @IsStocked bit
SELECT * FROM Products p WHERE p.LastSeen > GETDATE() - 30
This returns all _Products_ that have been seen within the last 30 days.
My question is, I would like the `p.LastSeen > GETDATE() - 30` clause to only apply when `@IsStocked = true`.
This is part of a larger query, and I'd like to achieve this without using IF/ELSE statements (i.e. if `@IsStocked = false` the `p.LastSeen > GETDATE() - 30` section of the WHERE clause is ignored completely).
Thanks! | DECLARE @IsStocked bit
SELECT * FROM Products p
WHERE @IsStocked = 0 OR (p.LastSeen > GETDATE() - 30); | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 1,
"tags": "sql, sql server 2008, where clause"
} |
Java for loop with an ArrayList
Here is the contents of my ArrayList `contain`
HPDH-1,001, Check-out date: 7/7/7
JTI-1,001, Check-out date: 7/7/7
My code:
for (int i = 0; i < contain.size(); i++) {
if (contain.get(i).contains(code)) {
System.out.println(contain.get(i));
}
}
The thing is my variable code was String "JTI-1" Why isn't it giving me the JTI-1 output? I am trying to get it to display the value of the variable code. I want to remove the contain.get(i) if it would just give me the one I typed in. | The code is correct assuming List of strings. `I have not modified any of your source code just to give you idea that it works fine.`
List<String> contain = new ArrayList<String>();
contain.add("HPDH-1,001, Check-out date: 7/7/7");
contain.add("JTI-1,001, Check-out date: 7/7/7");
String code = "JTI-1 ";
for (int i = 0; i < contain.size(); i++) {
if (contain.get(i).contains(code.trim())) {<---Use trim it is possible that code may have extra space
System.out.println(contain.get(i));
}
} | stackexchange-stackoverflow | {
"answer_score": 11,
"question_score": 12,
"tags": "java, for loop, arraylist"
} |
"Пока чайник закипит" or "пока чайник не закипит"
There is a russian joke the optimist is that who says "Ждать, пока чайник закипит" and pessimist is, in turn, a person who'd prefer to say "Ждать, пока чайник **не** закипит".
Those two form are opposite grammatically and are identical in this context. For example, we can also say "пока стану миллионером" and "пока не стану миллионером".
My question is - are both variants indeed equally accepted, how this phenomenon of loss of negation is called? Is it typical for Russian, or for other Slavic languages as well? | These are different conjunctions.
Rosenthal et al., _Справочник по правописанию, произношению и литературному редактированию_ , §209.2:
> Различается употребление в придаточных предложениях времени союза _пока_ и сложного союза _пока не_
>
> …
>
> Употребление в этих значениях союза _пока_ вместо _пока не_ придает высказыванию разговорный характер, например:
>
>> _Они говорили до поры, пока келейник принес самовар... (Горький)_
>>
>> _Пей, Григорий Пантелеевич, пока почернеешь... (Шолохов)._
The literary norm prescribes to use _пока не_ in your sentence. | stackexchange-russian | {
"answer_score": 12,
"question_score": 14,
"tags": "грамматика, terminology, other languages"
} |
De-installing windows?
I'm **totally** new to the linux world, so I know it might not be a wise decision to completely de-install windows 10 (which I have in dual boot with Juno).
Still, despite of the nerving sound problem, which seems to happen only to me, since nobody answered my question about it, I'm feeling inclined to get rid of windows for good and keep elementary as the only OS.
How can I do that? | If it's an EFI install you can simply use a program like GParted or Gnome Disk Utility to delete the Windows partitions (not including the EFI partition) and then run 'sudo update-grub'. If you run 'sudo ls /boot/efi/EFI/ubuntu' what do you see? | stackexchange-elementaryos | {
"answer_score": 0,
"question_score": 0,
"tags": "system"
} |
Hidden Markov Models with C++
I've been looking into implementations of Hidden Markov Models in C++ lately. I was wondering If I could use any of the existing HMM libraries written in C++ out there to use with Action Recognition (with OpenCV)?
I'm tying to AVOID "re-inventing the wheel"!
Is it possible to use Torch3Vision even though(looks like) it was designed to work for speech recognition?
My idea is that, if we can convert the feature vectors into Symbols/Observations (using Vector Quantization - Kmeans clustering), we can use those symbols for decoding, inference, parameter learning (Baum–Welch algorithm). This way it would work with Torch3Vision in OpenCV.
Any help on this will be truly appreciated. | You can take a look at < for the theory behind HMMs. It's not hard to implement the algorithms yourself.
For a C-based version, you can take a look at my implementation, < which I've done for a Google Summer of Code project. | stackexchange-stackoverflow | {
"answer_score": 12,
"question_score": 16,
"tags": "opencv, machine learning, computer vision, hidden markov models"
} |
processing messages
I use a queue per message type. I have tended to create a windows service per queue to process those messages. Is this the best use of resources? I suspect not. How do you decide how many processes should service a queue(s)? | One thing to consider here is service levels. Does all of the data represented by the message types require identical processing service levels? Are some messages more important than others? Do some messages have latency requirement for delivery? Are some messages critical to the business whereas others not? Are the expected volumes of all message types different?
Currently the way you have things set up means that you can manage each of your message type channels as a separate concern, which allows you maximum flexibility to support all possible service level scenarios. However this comes as a cost of higher resource cost/more moving parts.
I would say that unless resource usage is a concern, then your set up is the best possible as you decouple your data processing channels from one another very effectively in this way. | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 1,
"tags": "wcf, windows services, msmq"
} |
Bash string comparison keeps returning wrong result
I am trying to find out why my comparison logic keeps failing. I keep getting **no match** with each attempt.
#!/bin/bash
AddComponentToComponent "home-navbar" "app"
...
AddComponentToComponent() {
if [[ "$1" == "home-navbar" ]] && [[ "$2" == "app" ]]; then
echo "match"
else
echo "no match"
fi
} | The match is working according to the comparison but your example will not work because you have declared the function after the call.
If you desire this order in your code then you could declare a `main` function
#!/bin/bash
main() {
AddComponentToComponent "home-navbar" "app"
}
AddComponentToComponent() {
if [[ "$1" == "home-navbar" ]] && [[ "$2" == "app" ]]; then
echo "match"
else
echo "no match"
fi
}
main "$@" | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": -2,
"tags": "bash"
} |
What does this pointer-heavy C code do?
Could someone explain to me what should two following lines do:
s.httpheaderline[s.httpheaderlineptr] = *(char *)uip_appdata;
++((char *)uip_appdata);
This is taken from uIP code for microcontrollers.
s - structure
httpheaderline - http packet presented as a string
httpheadrlineptr - integer value
uip_appdata - received ethernet packet (string)
If some more info is needed please let me know.
BTW. Eclipse is reporting an error on the second line with message _Invalid lvalue in increment_ so I'm trying to figure out how to solve this. | The intention behind first line is to grab a character pointed to by `uip_appdata`:
*(char *)uip_appdata
casts `uip_appdata` to `char*`, then dereferences it, thus taking the first character.
The second line tries to increment `uip_appdata`. The trouble is, it does not do it properly, because results of a cast cannot be incremented "in place".
Here one way of doing it that works:
char *tmp = uip_appdata;
uip_appdata = ++tmp;
With this code fragment the compiler can take care of converting between pointer types in cases when the platform requires it.
Here is a demo of this concept on ideone. | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 3,
"tags": "c, pointers"
} |
How to generate random color names in C#
I need to generate random color names e.g. "Red", "White" etc. How can I do it? I am able to generate random color like this:
Random randonGen = new Random();
Color randomColor = Color.FromArgb(randonGen.Next(255), randonGen.Next(255),
randonGen.Next(255));
but I need the names and not all colors generated like this have a known name.
Thanks | Use `Enum.GetValue` to retrieve the values of the `KnownColor` enumeration and get a random value:
Random randomGen = new Random();
KnownColor[] names = (KnownColor[]) Enum.GetValues(typeof(KnownColor));
KnownColor randomColorName = names[randomGen.Next(names.Length)];
Color randomColor = Color.FromKnownColor(randomColorName); | stackexchange-stackoverflow | {
"answer_score": 94,
"question_score": 55,
"tags": "c#, random, colors"
} |
How to "Sum distinct" with DAX formula based on 3 columns? Microsoft PowerBI
I have been struggling with this for some time and are not able to solve this.
I have three columns in this small test dataset
**order_id**
**code**
_**weight**_ from which I need the distinct sum
I need to find a way to calculate the _distinct sum_ of **weight** for each **code** per **order_id**
; FIRSTNONBLANK(data[weight]; 0))
But I do not see any way of adding this _per_ **order_id** to the formula.
Any help will be appreciated
Thank you in advance | You are nearly there. The simplest modification would be to change your measure to this:
Total = SUMX(DISTINCT(data); FIRSTNONBLANK(data[weight]; 0))
Notice here that the table I'm passing into `SUMX` is the full `data` table rather than just a single column of that table so that `order_id` (and `weight`) is part of determining whether a row is distinct.
If you have other columns and want to only use `order_id` and `code` to determine distinct rows, then instead of `DISTINCT(data)` you could use `SUMMARIZE(data, data[order_id], data[code])`, which groups by the specified columns. | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 1,
"tags": "powerbi, dax, powerbi desktop"
} |
Javascript regex OR |
I'm currently searching how to write correctly a regex for this application :
1 - A number without "." with a length of 1 to 5 digits => `/^(\d{1,5})$/`
2 - A number with "." with a length of 1 to 5 digits before the "." and 1 to 4 digits after the "." or a number starting with "." with a length of 1 to 4 digits after the "." => `/^(\d{1,5})?\.?(\d{1,4})?$/`
I tried to use a or operator "|", but it doesn't work ;( => `/^(\d{1,5})?\.?(\d{1,4})?$|^(\d{1,5})$/` I do not understand why, it's my first java script regex and i'm not sure to use well the "|" operator.
Following the answers I would like to obtain with **1** regex :
123 => ok
12345 => ok
123456 => not ok
12345.2156 => ok
123456.12 => not ok
12345.12345 => not ok
Thank you very much for your help. Have a nice day.
Etienne | Both rules rolled in to one:
^\d{1,5}$|^\d{0,5}\.\d{1,4}$
Here is a working example | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 4,
"tags": "javascript, regex, numbers, operators"
} |
Check if post is added manually or through wp_insert_post()
I might not be thinking this right but here is my situation:
* I have a custom post type called `events`.
* Some of my events are imported from an API and inserted through `wp_insert_post()` (in a plugin), some are added manually in the admin edit screen.
* On post saving I need to add some informations to the `post_meta` but **only if the post is added manually (through the admin edit screen)**.
So I am hooking into `save_post_events` and performing some security checks but I have no idea how to check if the request is only coming from the admin edit page because right now the `save_post` action triggers also if the post is added with the `wp_insert_post` function.
Any ideas?
Thanks | I have found a solution without adding any other metaboxes. I haven't thought about it but the import function in my plugin uses a `nonce` so I just check if my nonce is set or not.
Here is my `save_post_events` function:
add_action( 'save_post_events', 'wse_327066_example', 10, 3);
function wse_327066_example( $post_id, $post, $update ) {
if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE || $post->post_status == 'trash' || !current_user_can( 'edit_posts' ) || isset( $_POST['_import_nonce'] ) )
return;
# Now I can do whatever I want with posts saved from the admin edit screen...
} | stackexchange-wordpress | {
"answer_score": 0,
"question_score": 1,
"tags": "wp insert post, save post"
} |
Invalid 'X-Frame-Options' header encountered when loading
> How to resolve "Invalid 'X-Frame-Options' header encountered when loading "?!
when i insert the google map in our html code then I am getting the error which is describe in attached image.
!when i insert the google map in our html code then I am getting the error which is describe in attached image. | You don't control Google's HTTP headers, so you can't (short of getting a job where you do control them) make them use valid options. | stackexchange-stackoverflow | {
"answer_score": 13,
"question_score": 16,
"tags": "html, google maps"
} |
Defining class constant in PHP
I would like to define a class constant using a concatenation of an existing constant and a string. I can't predefine it because only scalars are allowed for predefining constants, so I currently have it as part of my constructor with a defined() function checking if it is already defined. This solution works but my constant is now unnecessarily global.
Is there a way to define a class constant at runtime in php?
Thank you. | See the PHP manual on Class constants
> The value must be a constant expression, not (for example) a variable, a property, a result of a mathematical operation, or a function call.
In other words, it is not possible. You could do it with runkit_constant_add but this sort of monkey patching is strongly discouraged. | stackexchange-stackoverflow | {
"answer_score": 9,
"question_score": 7,
"tags": "php, constants"
} |
[HTML][PHP] Upload from form
I would like to upload values from html into MySQL. This is my HTML code:
<form id="fr" class="fr" method="post" onsubmit="myFunction()">
<input id="ceg1" type="text" name="ceg" placeholder="Cég neve"><br>
<input id="ceg2" type="text" name="kontakt" placeholder="Kapcsolattartó neve"><br>
<input id="ceg3" type="email" name="" placeholder="Kapcsolattartó email címe"><br>
<input id="ceg4" type="text" name="" placeholder="Leírás (max. 200 szó)"><br>
<h1>Témakör</h1>
<input type="radio" name="menu" value="1">1</input><br>
<input type="radio" name="menu" value="2">2</input><br>
<input type="radio" name="menu" value="3">3</input><br>
<input type="submit" name="submit" value="submit"></input>
How can I upload the values to a MySQL or only into a php variable? | <form id="fr" class="fr" method="post" onsubmit="myFunction()">
<input id="ceg1" type="text" name="ceg" placeholder="Cég neve"></input><br>
<input id="ceg2" type="text" name="kontakt" placeholder="Kapcsolattartó neve"></input><br>
<input id="ceg3" type="email" name="" placeholder="Kapcsolattartó email címe"></input><br>
<input id="ceg4" type="text" name="" placeholder="Leírás (max. 200 szó)"></input><br>
<h1>Témakör</h1>
<input type="radio" name="menu" value="1">1</input><br>
<input type="radio" name="menu" value="2">2</input><br>
<input type="radio" name="menu" value="3">3</input><br>
<input type="submit" name="submit" value="submit"></input>
</form>
<?php
$ceg = $_POST["ceg"]; | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": -2,
"tags": "php, html, mysql"
} |
Hide element from loop (AngularJS)
I've got this code:
AngularJS:
$scope.languages = [
{ language: "English", i18n: "en" },
{ language: "Espanol", i18n: "es" },
{ language: "Polski", i18n: "pl" },
{ language: "Portugues", i18n: "pt" },
{ language: "Svenska", i18n: "se" },
];
HTML:
<li ng-repeat="lang in languages" id="langRow_{{lang.i18n}}">
<a href="#" id="lang_{{lang.i18n}}" ng-click="changeLang(lang.i18n);"><i class="flag-icon flag-icon-{{lang.i18n}} mr-sm"></i>{{lang.language}}</a>
</li>
and I want to hide an element from loop, for example:
$("#langRow_es").hide();
It doesn't work. How to solve this? | 1) If you want to use Angular, FORGET JQUERY.
2) USE ANGULAR.
Try this :
<li ng-repeat="lang in languages" ng-hide="lang.i18n=='es'" > | stackexchange-stackoverflow | {
"answer_score": 6,
"question_score": 2,
"tags": "javascript, jquery, angularjs"
} |
Twig check if value in array is true
I have an array which contains booleans. How do I search the array to see if one or more is true and then display the `<h1>` something once?
Here is my code so far
{% set guides =
[
product.is_user_guide,
product.is_product_guide,
product.is_installation_guide
]
%}
{% for guide in guides %}
{% if (guide) %}
<h1>There is a guide!</h1>
{% endif %}
{% endfor %}
In the above code it finds 2 values in the array to true and displays the h1 twice. How can I modify it so it only displays once? | You can use the _containment operator_ `in`:
{% set guides = [
product.is_user_guide,
product.is_product_guide,
product.is_installation_guide
] %}
{% if true in guides %}
<h1>There is a guide!</h1>
{% endif %}
Demo: < | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 2,
"tags": "php, arrays, twig"
} |
RoR user management & dictionary tutorial recommendations
I haven't touched ROR in close to 4 years.
I have an idea for an app that will rely on user input to build a dictionary, and other users can add to the dictionary - basically a wiki.
Can anyone suggest a good tutorial out there for get my head around creating user models, authentication and other basic stuff.
Also I read that rails 3.2 makes user authentication much more simple and stable. Sound right?
I'm on a mac running 10.7 and i have Xcode 4.3.2 and text mate - if any of that is useful info.
Thanks guys!
Adam | I really liked this railscast, you might too
< | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": -1,
"tags": "ruby on rails"
} |
How to know if a C++/CLI reflected parameter is long or int?
I'm reflecting a C++/CLI method that has the following signature:
void foo(long n);
This translates into C# as:
void foo(int modopt(IsLong) n);
How can I find if an _int_ parameter is actually a C++/CLI long by reflection? | Check the `ParameterInfo` instance's optional custom modifiers:
bool IsLongParameter(System.Reflection.ParameterInfo p) {
Type[] modifiers = p.GetOptionalCustomModifiers();
return modifiers.Contains(typeof(System.Runtime.CompilerServices.IsLong));
} | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": ".net, reflection, visual c++, c++ cli"
} |
Best approach to animate physics in Silverlight?
I am new to Silverlight and want to animate a ball that is shot out of a cannon then moves through the air under the laws of physics (so roughly, on an elliptical path).
My inclination is to use a callback timer and move the little ball every 50ms by changing its Canvas.LeftProperty and Canvas.TopProperty values. Is this the right approach or should I be using a DoubleAnimation? My resistance to using animations here is that I would have to create many different animation in succession.
Which path would a Silverlight guru take? | Have a look at a question I asked some time ago here the accepted answer gives a comparison of five different ways to do animation for games in silverlight linking to this blog. The article concludes that the method you choose will depend on a number of factors.
To answer you question I personally would use the dispatcher timer which is fired each time the screen re-draws and set the properties then to move the X and Y.
I also found Game Physics 101 a really good resource. | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 3,
"tags": "silverlight, animation"
} |
Hide code from jar file
I have made a jar file for a software that I need to use. The problem is that since it is a jar file, anyone can get .class files and decompile them to get the actual java code.
Could some one please point out how to keep this java code secure. I have tried converting this jar to exe using launch4j but noticed that it just packs everything to exe. This exe can be extracted and then decompiled to get the actual java code.
I just need code to be secure, whether by converting to exe or by any other method. Please help.
Thanks in advance | What you need is Java Code obfuscator which will change the Java code without changing the actual functions.
Check ProGuard which does that. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": -1,
"tags": "java"
} |
How can I avoid using a variable here?
I want to create a canvas element and get it's context. I tried everything, but can't get rid of the `buffer` variable. It's driving me insane. Can you help me?
(function(buffer){
document.body.appendChild(
buffer=document.createElement("canvas")
)
canvas=buffer.getContext("2d")
})() | What's wrong with the variable? Anyways, you can do:
var canvas = document.body.appendChild(document.createElement("canvas"))
.getContext("2d");
since `Node.appendChild` returns the node that was appended. | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 0,
"tags": "javascript, dom, variables"
} |
How to deal with geopy's query limit?
I am doing a project, in which I need to convert coordinates to street name. We use geopy package but we find that the query limit is really a problem. I have 70K lines of coordinates and I hope to finish converting in 3 days. How can I do this in 3 days? or is there other python package that can do same job without limit? | Geopy just relies on web API to do the conversion. And, All web API have limits on the amount of queries you can do, particularly if they are free.
You can either look for an API which has higher query limits (probably in exchange for a fee), or, for instance, install Open Street maps Nominatim on you own server and do as many queries as you like (the process is rather lengthy though). | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 1,
"tags": "python 3.x, geocoding"
} |
Words of Torah Need Not Be Enunciated
Ritva (commentary to Brachos 15b) writes that Torah need not be enunciated out loud during study. Which other Rishonim espouse this view?
* * *
I am not asking regarding side issues such as verbal recitation facilitating memorization. I am only asking about the actual mitzva itself. | Encyclopedia Talmudis (הרהור כדבור) says that the Meiri holds this way (it does not mention the Ritva) and any Rishon who holds the Halacha is like Ravina that thought is equivalent to speech in regards to Shema would hold the same for words of Torah. | stackexchange-judaism | {
"answer_score": 4,
"question_score": 1,
"tags": "halacha, sources mekorot, torah study, rishonim, ritva"
} |
Is SQL relevant to statisticians' work?
I hope this is the right place for posting this, but if not, please let me know!
I recently took a second class in Python programming which, toward the end, also taught a little bit of SQL. As it turns out, SQL was the part of the class that I enjoyed the most. So, over the summer, I am thinking of acquiring a Microsoft certification in SQL. However, before engaging myself in that, I wanted to ask if this certification is likely to benefit my career plans directly or indirectly (I am planning to pursue a Masters in Statistics, with probably some data science component in a couple years).
Do statisticians use SQL in their work? Is it reasonable to assume that SQL might become prevalent in statisticians' work in 10 or so years? | > Do statisticians use SQL in their work?
Yes! I would say it is already prevalent.
Four indications:
* One is how SQL queries are now easily accessed from within R: Database Queries with R.
* You are apparently already familiar with Python and SQL interfaces, e.g., SQLite.
* There is a DataCamp course Introduction to SQL.
* If you are on the job market as a statistician, anecdotally it is now common to require SQL knowledge and experience. | stackexchange-matheducators | {
"answer_score": 5,
"question_score": 3,
"tags": "graduate education, statistics"
} |
Storing Lambdas in Dictionary
I am trying to store lambda functions in a python dictionary. It seems that the loop overwrites all of the data stored in the dictionary with the last lambda. For example:
example_dict = {}
for i in range(5):
example_dict[i] = lambda x: x + i
for key, func in example_dict.items():
print(key, func(10))
Should output
0 10
1 11
2 12
3 13
4 14
But the actual output is:
0 14
1 14
2 14
3 14
4 14
This is very interesting to me. Anybody know why the last lambda function overwrites all of the other data in the dictionary? | It's not overwriting the last `lambda`, they _all_ point to the final value of `i` in the `for` loop because of how closures work. You can avoid it by giving the `lambda` functions a default argument:
example_dict = {}
for i in range(5):
example_dict[i] = lambda x, i=i: x + i
for key, func in example_dict.items():
print(key, func(10))
Output with change:
0 10
1 11
2 12
3 13
4 14 | stackexchange-stackoverflow | {
"answer_score": 7,
"question_score": 4,
"tags": "python, lambda, closures"
} |
How could SUM(column) give incorrect results in MySQL?
I have the following simple MySQL query, called from PHP:
SELECT foo_id, SUM(number_of_guests)
FROM guests
WHERE foo_id = $foo_id
GROUP BY foo_id
This works fine, except for one $foo_id, which returns about 2.5 times greater than the sum of the number_of_guests field.
What could cause this behavior for only a certain value of $foo_id?
Is there a better way to do this? | The problem is that there was one row with a large value for number_of_guests. I didn't see in in browsing the data because there are a few hundred rows. It didn't show up when I copied and pasted from HTML page into Excel because that row was missing most of the other columns, and the HTML page has all the columns.
Thanks for all your help! | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "mysql, sql, group by, sum"
} |
Cylindrical Coordinates with triple integral
Use cylindrical coordinates to evaluate:
$$\int_0^4\ \int_0^{\frac{\sqrt2}2} \int_x^{\sqrt{1-x^2}} e^{-x^2-y^2} dydxdz$$
I have tried to solve for $\theta$, $r$ and $z$.
I have obtained $0\leq\theta\leq\pi/4$, $0\leq r\leq\sec(\theta)/\sqrt{2}$ and $0\leq z \leq 4$.
But I am not obtaining the correct solution. Are my integrals correct or is it wrong? | The lower bound of $y$ is $x$
$y = x \implies \tan \theta = 1 \text{, i.e } \theta = \frac{\pi}{4}$
$x \geq 0$ means we are in first quadrant so $\theta \leq \frac{\pi}{2}$.
The upper bound of $y$ is $\sqrt{1-x^2} \implies x^2+y^2 \leq 1 \implies r \leq 1$.
So it should be,
$\displaystyle \int_{\pi/4}^{\pi/2} \int_0^4 \int_0^1 r \ e^{-r^2} \ dr \ dz \ d\theta = \frac{(e-1) \pi}{2e}$ | stackexchange-math | {
"answer_score": 1,
"question_score": 0,
"tags": "integration, multivariable calculus, multiple integral, cylindrical coordinates"
} |
Donut chart in highcharts appears messed up on export
We are using highcharts as our charting library. It's great and exporting works well in all scenarios except one. We have a donut chart with two levels. When it is rendered in the browser it shows up fine:
!in browser
If you now export this chart using the default highcharts service it shows a bit like this: !exported image
Anyone know why this is happening and if there is any way we can fix this? | My mistake in the configuration was when I was dynamically updating the colour:
chart.series[0].data[s].update({color: "#FFFFFF")}, false);
This didn't just mean I was updating the color but also the whole point. This meant that by running the above I was running y to nothing! Although the chart displayed ok the data sent to the exporting service was with unset values for the slices.. hence the empty slices in the chart. to fix it I had to do something like:
chart.series[0].data[s].update({
color: "#FFFFFF",
y: chart.series[0].data[s].y,
name: chart.series[0].data[s].name,
)}, false); | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "highcharts"
} |
Set the sorting properties of gridview true but still columns are not becoming links
I have to do a sorting on headers of the gridview.
i have set the sorting property to true and also implemented the onsorting event.
But my headers are not coming up as links,what could be the reason? | Maybe your columns content is not sortable, for instance you have images. For that as a trick you can associate each image an index and bound the grid column to the index, rather than image. | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "c#, datagridview"
} |
Value of $\sum_{n=0}^{\infty} \frac{(-1)^n}{\ln(n+2)}$
While testing implementations of Wynn's $\epsilon$-algorithm and Levin's u-transformation I need the value of $$\sum_{n=0}^{\infty} \frac{(-1)^n}{\ln(n+2)} \cdot$$ The results of my algorithms are in agreement with the Pari/GP **sumalt** value of $0.92429989722293885595957$. But Wolfram Alpha gives the following approximated sum when entering
sum (-1)^n/(ln(n+2))
(a direct link from Math.SE will be mangled and does not work, here is the eq.):
$$\sum_{n=0}^{\infty}\dfrac{(-1)^n}{\log(2+n)}\approx1.00766524110155\ldots$$
Questions:
* Are the values from Pari and my algorithms correct?
* Is there a closed form analytical result? | For $x \in (0,1)$ consider
$$f(x) = \sum_{n=2}^{\infty} \frac{(-1)^n}{\log{(n+2)}} x^{\log{(n+2)}}$$
Then
$$f'(x) = \frac{1}{x} \left [ 1-\left(1-2^{1+\log{x}}\right) \zeta(-\log{x})\right]$$
where $\zeta$ is the Riemann zeta function. Using $f(0)=0$, I get that the sum may be expressed in terms of the following integral:
$$\int_0^{\infty} du \left [ 1-\left ( 1 - \frac{1}{2^{u-1}}\right ) \zeta(u)\right]$$ | stackexchange-math | {
"answer_score": 7,
"question_score": 6,
"tags": "sequences and series, summation, convergence acceleration"
} |
How do I place the ~/.composer/vendor/bin directory in your PATH using .zshrc
This may be a very noob question, but I'm trying to install Homestead on my Mac. I'm following installation steps via < however there is a point in the installation process where it state "Make sure to place the ~/.composer/vendor/bin directory in your PATH so the homestead executable is found when you run the homestead command in your terminal." How do I do this using zsh? Thanks! | in whichever profile you're using (.zprofile or .profile or whatever), you would add the line:
export PATH = ~/.composer/vendor/bin:$PATH
then reload your profile
source ~/.zprofile | stackexchange-stackoverflow | {
"answer_score": 10,
"question_score": 10,
"tags": "laravel, zsh"
} |
Ruby map to append dot at the end
I have the below line
new_records = records.map{|record| record.name.to_s.}.sort
which outputs
# Current Output:
new_records = ["ab-12.cd.net", "de-34.fg.net"]
How can I make it to return with a `.` (dot) at the end?
# Desired Output:
new_records = ["ab-12.cd.net.", "de-34.fg.net."]
I can do it using another map, for example
new_records = records.map{|record| record.name.to_s.}.sort
new_records2 = new_records.map { |record| "#{record}." }
But looking for an efficient way of achieving it using the 1st map itself. | this would work:
new_records = records.map{|record| "#{record.name.to_s}." }.sort
you can also use `+` like this:
new_records = records.map{|record| record.name.to_s + "." }.sort | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 2,
"tags": "ruby, string, loops, string concatenation"
} |
sub domain records
**UPDATE 2:**
Our website is created on RedHat Linux. We are using Apache as the web server software. Basically, we have our website on a LAMP configuration. We use rackspace managed hosting, but they do not manage our dns records. Our DNS records are managed by verizon, for which I have access too also.
**UPDATE 1:**
How do I create a sub-domain for our existing domain? If our existing domain was companyname.com, we would want a subdomain like users.companyname.com.
**ORIGINAL QUESTION:**
I've been given access to our dns records and need to create a sub domain. We currently have
companyname.com and www.companyname.com go to our web host at say 00.000.000.00
_How do I create a new dns record so we can point users.companyname.com to a folder on our server at 00.000.000.00 instead of it going to the webroot of 00.000.000.00?_ | DNS will only point you to the IP/server. Then you must use Apache to direct to a different folder. First setup the CName or A record with Verizon's interface for DNS. Point to the server that will be hosting the site. You can confirm that it works by pinging the name and getting the correct IP back.
Then the next step isn't related to DNS. It's Apache related. If you still have questions about that, start a fresh question or re-flag this as an Apache question. | stackexchange-serverfault | {
"answer_score": 1,
"question_score": 1,
"tags": "domain name system, domain, subdomain"
} |
Install LTE stick from Huwei 3772h on Raspberry PI with suisse telecom
Is there a way to use a LTE on Raspberry PI or Linux in general even if there are only .exe files on that stick?
Did anyone get a LTE stick from switzerland to work with his raspberry pi? | Exe files are indeed windows-only. However, many LTE sticks have Linux drivers, either released by the manufacturer, or created by the community. Ubuntu Wiki has a list of such supported sticks. You should find out what chipset your stick has (`lsusb` reports Vendor ID / Product ID which you can compare with the values from the list). If it is supported, check the "Notes" column for hints on how to get it to work. Edit your question to include details (VID/PID and what you have tried) if it still won't work, perhaps the community will be able to help.
For sticks which present themselves as mass storage (such as yours) the first step is to use `usb_modeswitch` to get it connected as a communication device instead of a thumb drive.
If it's not supported, you're most likely out of luck. I would buy a supported model and plug your SIM card in it: chances are, it will work fine on your operator's network. | stackexchange-raspberrypi | {
"answer_score": 2,
"question_score": 2,
"tags": "usb, raspberry pi desktop"
} |
How to redirect to a specific route from within ExpressJS API code?
I want to be able to redirect my MEAN app to the Login page whenever there is no valid login.
I have a component, which on `ngOninit()` calls an API route.
The API route looks like:
router.get("/route", isLoggedIn, (req, res) => {
});
Where `isLoggedIn` is:
function isLoggedIn(req, res, next) {
if (req.isAuthenticated()) {
return next();
} else {
console.log("Not Logged in");
res.redirect("
}
}
When `res.redirect(" is executed, it throws an error in the console: "Template parse error". I guess this has something to do with the component which called the API waiting for the response from the API.
What's the best way to accomplish this? | Handle it in your MEAN app, redirect the user to login page from angular and from API return a JSON response.
res.status(401).json({error: "Unauthorized Access"});
In you angular side, in the response of this API call check if you get this error then redirect user to login page. you could do this by using angular service. `$location`
$location.url('/login');
For generic solution to check authentication on every route you should use `http interceptor`. Please have look at following stackoverflow question:
> AngularJs route authentication | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 0,
"tags": "node.js, angular, express, routes"
} |
How to output T? not Nullable<T> in EF Reverse Engineer Code First?
The "Reverse Engineer Code First" functionality of Entity Framework Power Tools, Beta 2 is very good and I am working on customising the Reverse Engineer Templates.
In Entity.tt, take a look at the following line (line breaks introduced):
<#= Accessibility.ForProperty(property) #>
<#= code.Escape(property.TypeUsage) #>
<#= code.Escape(property) #>
{ get; set; }
For a database column named "SomeDate" of type datetime, you will have the following code outputted:
public Nullable<System.DateTime> SomeDate { get; set; }
How can I modify the Entity.tt code to produce this instead:
public DateTime? SomeDate { get; set; }
Thank you,
R. | As podiluska mentioned, you need to edit EF.Utility.CS.ttinclude (you can see that this is imported by Entity.tt if you follow the "Customize Reverse Engineer Templates" instructions here)
On my machine it is here:
C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\Extensions\Microsoft\Entity Framework Tools\Templates\Includes
Around line 127, replace
return String.Format(CultureInfo.InvariantCulture, "Nullable<{0}>", typeName);
With
return String.Format(CultureInfo.InvariantCulture, "{0}?", typeName);
**Make sure you test this. It worked fine for me, but I can't guarantee that it will work for all nullable types. Any comments would be appreciated and I will edit this post as appropriate** | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 2,
"tags": "entity framework, ef code first, t4"
} |
Merge/Combine two 'overlay' layers in GIMP
Working on my image in GIMP, I have the following configuration:
Top Layer (Normal)
Layer 1 (Overlay)
Layer 2 (Overlay)
Background
Since Layer 1 and Layer 2 are both of the same blend mode and transparency I would like to 'combine' them into one layer; doing this however results in a very different effect to what I want. (Understandable when looking at the Overlay equation: <
**Is it possible to combine two layers, such that the effect of overlaying the resultant layer is equivalent to overlaying the first layer, then the second? If so, how do I do it?**
Thanks! | Sorry, but the answer is no as far as I know...
The only exception of course is when the two layers don't "overlap" one another (i.e. they don't have non transparent parts one above the other) - in that case change both layers to normal mode, merge them, and then change the merged result to be in overlay mode. | stackexchange-superuser | {
"answer_score": 1,
"question_score": 0,
"tags": "gimp, layers, image editing"
} |
Input hidden value propery when value has spaces
I have a form with the hidden value holding onto the name of a question that is stored in a mysql database. The issue I am having is that the hidden value only holds onto the first part of the name. For example, in my template:
% for d in data
<input type="hidden" name="question_name" value={{d["name"]}}>
% end
`d["name"]` would be something like "math question". When I checked the `question_name` value on the server, and the hidden input value in jQuery, the result is `math` and it leaves out anything coming after the first word. What could be causing this? | You need to wrap it with quotes other ways the remaining part is considered as another attribute of the tag.
% for d in data
<input type="hidden" name="question_name" value="{{d["name"]}}">
% end | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 1,
"tags": "jquery, python, html, bottle"
} |
Planet orbits: what's the difference between gravity and centripetal force?
My physics teacher says that centripetal force is caused by gravity. I'm not entirely sure how this works? How can force cause another in space (ie where there's nothing).
My astronomy teacher says that gravity is (note: not like) a 3D blanket and when you put mass on it, the mass causes a dip/dent in the blanket and so if you put another object with less mass it will roll down the dip onto the bigger mass. Is this true and is this what causes the centripetal force. | Simple answer: gravity _is_ a centripetal force, and can be envisaged clearly as such in Newtonian mechanics.
_Centripetal_ just means a force that is "radially inwards" ("directed towards the centre"). The electric force between two objects of opposite charges, for example, is also clearly centripetal. (It's slightly harder to define "centripetal" for the magnetic force.)
Your astronomy teacher is referring to Einstein's theory of general relativity. His description is loosely an overview of the topology (fabric) of space-time and how it interacts with matter/energy - the manifold is however 4-dimensional, not 3D.
In fact, test particles (particles which do not really disturb the gravitational field) in general relativity follow a geodesic. This is effectively a generalisation of a straight line (shortest route) of normal Euclidian space to the curved space of GR, and may be seen as the source of centripetal force in Newtonian physics. | stackexchange-physics | {
"answer_score": 9,
"question_score": 7,
"tags": "forces, gravity, centripetal force, celestial mechanics"
} |
Transform the equation $(x+y)\frac{\partial u}{\partial x} - (x-y)\frac{\partial u}{\partial y} = 0$ with $s = \ln\sqrt{x^2+y^2}$, $t = \arctan(y/x)$
Let $u(x, y)$ be a $C^1$-smooth function. Transform the equation
\begin{equation} (x+y)\frac{\partial u}{\partial x} - (x-y)\frac{\partial u}{\partial y} = 0 \end{equation}
by introducing the new variables $s = \ln\sqrt{x^2+y^2}$, $t = \arctan(y/x)$. Use this to write down the general solution to the equation.
I've tried multiple things with no luck as I think I'm way off. I really have no idea how to rewrite the equation in terms of $t$ and $s$. Would love some help, thanks. | \begin{align} \frac{\partial u}{\partial x} &= \frac{\partial u}{\partial s} \frac{\partial s}{\partial x}+ \frac{\partial u}{\partial t} \frac{\partial t}{\partial x} \\\ &= \frac{x}{x^2+y^2}\frac{\partial u}{\partial s}- \frac{y}{x^2+y^2}\frac{\partial u}{\partial t} \\\ \frac{\partial u}{\partial y} &= \frac{\partial u}{\partial s} \frac{\partial s}{\partial y}+ \frac{\partial u}{\partial t} \frac{\partial t}{\partial y} \\\ &= \frac{y}{x^2+y^2}\frac{\partial u}{\partial s}+ \frac{x}{x^2+y^2}\frac{\partial u}{\partial t} \\\ (x+y)\frac{\partial u}{\partial x}-(x-y)\frac{\partial u}{\partial y} &= \frac{(x+y)x-(x-y)y}{x^2+y^2} \frac{\partial u}{\partial s}+ \frac{(x+y)(-y)-(x-y)x}{x^2+y^2} \frac{\partial u}{\partial t} \\\ &= \frac{\partial u}{\partial s}-\frac{\partial u}{\partial t} \end{align} | stackexchange-math | {
"answer_score": 1,
"question_score": 0,
"tags": "ordinary differential equations, multivariable calculus"
} |
Port Direction - I/O
I have one question regarding the direction of Port Pin (GPIO). Is it mandatory to change the direction of port pin to input in order to read the value from that port. Keeping the port direction as output, should we not read the value from Port? Reason because, I am trying to read the value from a different driver outside the controller board on SPI communication. In order to read the value from it, clock signals needs to be sent out.This is being done by sending 0xFFFF with direction as input and then value is read. But my problem is, in order to read the value from device, if I send 0xFFFF (to generate clock signal) with Port direction as output, I am still able to read the value from sensor. So is it real mandatory to change the port direction to input to read the value? What consequences may I face if I don't do this? | This really depends on the specific device.
Many devices do allow you to read the state of an output pin. This is particularly useful for pins set to open-collector/drain (drive low only) as when outputting high, the hardware pin is set high-Z and an external connection is allowed to pull the pin low.
On the other hand, if the pin is set push/pull (driving both high and low), you had better not drive it externally as you can create a fight and damage one or both devices. Here, if want to read an external state, you must set the pin to input.
There are some devices that don’t have an explicit input state. Instead, you must set it to open-collector output and high output to place it in a high-Z state.
There may be some devices where when a pin is set to output, reading simply returns the set output state, regardless of the actual level of the hardware pin.
If you want a specific answer, you need to specify what device you’re asking about. | stackexchange-electronics | {
"answer_score": 2,
"question_score": -3,
"tags": "port"
} |
Is there a simple, NIO2 only way to convert from URL to Path
I want to copy a directory (including content) from a URL I get from
Some.class.getClassLoader().getResource("folder");
which returns either `jar:file:/D:/../some.jar!/someparent` or `file:/D:/../someparent`
I thought of a `FileSystem` (for jar intern dirs) and recursively copying with `Files.walkFileTree(..)`.
Is it possible to modify `jar:file:/D:/../some.jar!/folder` to get a FileSystem NIO2 only? | What I was looking for was something like:
JarURLConnection connection = (JarURLConnection) sourceUrl
.openConnection();
Paths.get(connection.getJarFileURL().toURI()); | stackexchange-stackoverflow | {
"answer_score": 2,
"question_score": 2,
"tags": "java, url, io, path, nio2"
} |
PHP json_encode umlauts
I'm getting json strings from an HTTP API. The content type is Content-Type: application/json; charset=UTF-8.
I then proceed to write the strings to a file using.
fwrite($fp, json_encode($post));
The strings contain encodings for umlauts as follows.
> Au\u00dfenministerium verh\u00e4ngte Reisewarnung f\u00fcr Kroatien in Kraft getreten.
This should be.
> Außenministerium verhängte Reisewarnung für Kroatien in Kraft getreten.
**How can I encode the strings to write umlauts to files and not their encoding?**
I tried the following.
<?php
$string = "Au\u00dfenministerium verh\u00e4ngte Reisewarnung f\u00fcr Kroatien in Kraft getreten.";
$string = utf8_encode($string);
echo $string;
The output of this script still shows the encoding. | That is the default behaviour of the `json_encode` function, but you can override this by specifying the `JSON_UNESCAPED_UNICODE` option. So for example:
json_encode("Außenministerium", JSON_UNESCAPED_UNICODE);
And in your code you should do:
fwrite($fp, json_encode($post, JSON_UNESCAPED_UNICODE));
Also check out which other options you can use in the documentation | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 2,
"tags": "php, json, encoding, utf 8"
} |
クロージャーから循環参照によるメモリリーク
SwiftUILabel
@IBOutlet weak var log: UILabel!
Alamofire.request(.GET, " { response in
switch response.result {
case .Success:
if let jsonData = response.result.value {
let json = JSON(jsonData)
for (_,value) in json {
self.log.text = self.log.text! + "\n" + value[1].string!.stringByRemovingPercentEncoding!
}
}
case .Failure(let error):
print(error)
}
}
self.log.text
| `self``self`()
****
AlamofireLeaks
(Xcode Leaks )
100%`self`
(`self``self`)
Alamofire.request(.GET, " { [weak self] response in
switch response.result {
case .Success:
if let jsonData = response.result.value {
let json = JSON(jsonData)
for (_,value) in json {
self?.log.text = self?.log.text! + "\n" + value[1].string!.stringByRemovingPercentEncoding!
}
}
case .Failure(let error):
print(error)
}
}
(`[weak self]``self.log``self?.log`)
| stackexchange-ja_stackoverflow | {
"answer_score": 0,
"question_score": 1,
"tags": "swift, クロージャ, 循環参照"
} |
VMware hypervisor license
can I use VMware vsphere hypervisor license on multiple host on different network? Apologize that one license is used in a farm in India and I will use the same license in a farm in UK. Obviously I ask if is technically possible. Thanks | It's technically possible and will work, but definitely not ethical or legal. | stackexchange-serverfault | {
"answer_score": 2,
"question_score": -1,
"tags": "vmware esxi, vmware vsphere, vmware server"
} |
How to put generic Type (T) as parameter?
I have this error:
Severity Code Description Project File Line
Error CS0246 The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?)
on the method signature for this method:
public static void SendMessage(string queuName, T objeto)
{
QueueClient Client =QueueClient.CreateFromConnectionString(connectionString, "Empresa");
BrokeredMessage message = new BrokeredMessage(objeto);
message.ContentType = objeto.GetType().Name;
Client.Send(new BrokeredMessage(message));
} | You forgot to specify the type parameter. You can do that in 2 ways:
Either you define them at the method definition (which is the way to go in your case, because your method is static):
`public static void SendMessage<T>(string queuName, T objeto)`
Or you can specify them on the class definition (for instance methods):
class MyClass<T>{
public void SendMessage(string queuName, T objeto){}
} | stackexchange-stackoverflow | {
"answer_score": 3,
"question_score": 0,
"tags": "c#, azure, servicebus"
} |
Best Practice for Foreign Key column position in table
This might be a silly question, but here goes:
Is there a standard or best practice that describes the order of foreign key column in a mssql table?
I for one like the idea of the PK being the very first column in the table followed by all the foreign keys and then all other columns thats relevant to that table.
Another way of doing it is having the PK as the very first column then all the supporting columns and then all foreign keys...
I guess it really doesn't matter, but I would like to get a standard across my organisation. | Interesting idea, but personally I think that having "a standard across my organisation" for this would do more harm than good.
Training and best practices sound fine, but a blindly enforced rule is "considered harmful". | stackexchange-stackoverflow | {
"answer_score": 1,
"question_score": 9,
"tags": "sql, database, design patterns, database design"
} |
How to interpret = and === in the same line?
I've come across this snippet of code
render: function() {
var boards = [];
for (var ii = 0; ii < this.props.numBoards; ii++) {
// We can compare to state here so we're no longer always selecting the first board.
var isSelected = ii === this.state.selectedIndex;
boards.push(
<Board index={ii} selected={isSelected} />
);
}
How is the line `isSelected = ii === this.state.selectedIndex` executed?
Here's the full code: < | The following code is executed in 2 steps
isSelected = ii === this.state.selectedIndex
1. ii === this.state.selectedIndex // comparator operator
2. isSelected = (result of step 1) // assignment operator | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 3,
"tags": "javascript, reactjs"
} |
Overlay video on top of Image - Do not resize Video, simply create a "larger" canvas around video
Is the following possible with ffmpeg?
Basically I want to leave the original video size alone, just make the video centered over a larger image, so it creates a border effect, as per following: ![enter image description here]( | The overlay filter can do the trick:
ffmpeg -i background.png -i input.mp4 -filter_complex "overlay=(W-w)/2:(H-h)/2" output.mp4 | stackexchange-superuser | {
"answer_score": 1,
"question_score": 1,
"tags": "ffmpeg, video, video editing"
} |
How do I find the iOS Product Bundle Identifier without XCode?
I'm on a linux machine and am unable to run XCode. I have a React Native application. Based on what I've read online, the only way to view the Product Bundle Identifier is to run XCode which isn't possible for me. I need this for my app's Auth0 integration. I use expo to run the app. | Yes, it's possible. What you need to do is go to the ios folder (If you don't see it, you have to run expo eject), then go into the chatapp.xcodeproj directory, and open the project.pbxproj as a plaintext file. After that, look for "PRODUCT_BUNDLE_IDENTIFIER" and you should find what you're looking for! | stackexchange-stackoverflow | {
"answer_score": 0,
"question_score": 0,
"tags": "ios, react native, expo, auth0"
} |
autotools: Enable compiler warnings
for an autotools-based C project, I'd like to get some more warnings from the compiler (e.g. at least -Wall in CFLAGS). What is the prefered way to enable compiler flags without breaking anything? Is there a m4 macro that tests if a given compiler flag is understood by the compiler? With such a macro I could do
TEST_AND_USE(-Wall -Wextra <other flags>)
Thanks | Widely used is the attributes.m4 CC_CHECK_CFLAG_APPEND macro from the xine project. Although, you often find variants (since it's quite simple) written directly in configure.ac | stackexchange-stackoverflow | {
"answer_score": 4,
"question_score": 5,
"tags": "c, compiler warnings, autotools"
} |
Google Master Tool: How allow external links in robots.txt
I have a problem with google rendering.
Googlebot couldn't get all resources for this page. Because it's blocked by its own google `robots.txt` file.
Here's an example of an external link. `
`
![Google robots.txt](
Can I allow this in my website using my own `robots.txt`? So I can avoid the error. | No. You can't control which URLs other websites ask bots to avoid. | stackexchange-webmasters | {
"answer_score": 2,
"question_score": 1,
"tags": "google search console, googlebot, google maps"
} |
Finding the centre of the circle on the complex plane
The centre of the circle represented by $|z+1|$=$2|z-1|$ on the complex plane is
(a)0
(b)5/3
(c)1/3
(d)None of these
What I've tried so far in attached in the pic below. Please refer to it
^2+y^2}=2\sqrt{(x-1)^2+y^2}$$ to $$(x+1)^2=4(x-1)^2.$$
It should be $$(x+1)^2+y^2=4\left((x-1)^2+y^2\right)\implies (x+1)^2+y^2=4(x-1)^2+\color{red}{4}y^2$$ After this, try to have a form of $(x-a)^2+(y-b)^2=r^2$. | stackexchange-math | {
"answer_score": 2,
"question_score": 0,
"tags": "complex numbers"
} |
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