Python modules not installing
Question: I had some code that was running just fine, and over the course of the day, I
broke something, and now I cannot install any python modules. Specifically, I
need numpy, matplotlib, and pillow. I cannot install any of them.

But the weird part is that they both appear to install just fine:

    
    
    $ sudo pip install numpy
    Collecting numpy
      Downloading numpy-1.11.0-cp27-cp27mu-manylinux1_x86_64.whl (15.3MB)
        100% |████████████████████████████████| 15.3MB 94kB/s 
    Installing collected packages: numpy
    Successfully installed numpy-1.11.0
    

Or when I try:

    
    
    $ sudo apt-get install python-numpy
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    Suggested packages:
      python-nose python-numpy-dbg python-numpy-doc
    The following NEW packages will be installed:
      python-numpy
    0 upgraded, 1 newly installed, 0 to remove and 20 not upgraded.
    Need to get 0 B/1,763 kB of archives.
    After this operation, 9,598 kB of additional disk space will be used.
    Selecting previously unselected package python-numpy.
    (Reading database ... 221259 files and directories currently installed.)
    Preparing to unpack .../python-numpy_1%3a1.11.0-1ubuntu1_amd64.deb ...
    Unpacking python-numpy (1:1.11.0-1ubuntu1) ...
    Processing triggers for man-db (2.7.5-1) ...
    Setting up python-numpy (1:1.11.0-1ubuntu1) ...
    

I am using python 2.7, and I am on Ubuntu 16.04.

    
    
    $ python
    Python 2.7.5 (default, May 12 2016, 13:11:58) 
    [GCC 5.3.1 20160413] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import numpy
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ImportError: No module named numpy
    >>> 
    

It does this for any module I try and install. Any help would be greatly
appreciated.


Answer: This is a result of the default `python` and the default `pip` not matching
up. To ensure that packages are being installed to the correct location, use:

`python -m pip install $PACKAGE`

This results in running the `pip` assigned to the desired `python` rather than
the first one found in your path.

