title: Using if statements to filter data?
body: <p>Lets say I have an excel document with the following format. I'm reading said excel doc with pandas and plotting data using matplotlib and numpy. Everything is great! </p>
  
  <p>Buttttt..... I wan't more constraints. Now I want to constrain my data so that I can sort for only specific zenith angles and azimuth angles. More specifically: I only want zenith when it is between 30 and 90, and I only want azimuth when it is between 30 and 330</p>
  
  <pre><code>Air Quality Data
  Azimuth Zenith    Ozone Amount
  230    50         12   
  0      81         10    
  70     35         7
  110    90         17
  270    45         23
  330    45         13
  345    47         6
  175    82         7
  220    7          8
  </code></pre>
  
  <p>This is an example of the sort of constraint I'm looking for.</p>
  
  <pre><code> Air Quality Data
  Azimuth Zenith    Ozone Amount
  230    50         12   
  70     35         7
  110    90         17
  270    45         23
  330    45         13
  175    82         7
  </code></pre>
  
  <p>The following is my code:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  import matplotlib.pyplot as plt
  import datetime
  
  P_file = file1
  out_file = file2
  out_file2 = file3
  
  data = pd.read_csv(file1,header=None,sep=' ')
  df=pd.DataFrame(data=data)
  df.to_csv(file2,sep=',',header = [19 headers. The three  that matter for this question are 'DateTime', 'Zenith', 'Azimuth', and 'Ozone Amount'.]
  df=pd.read_csv(file2,header='infer')
  mask = df[df['DateTime'].str.contains('20141201')] ## In this line I'm sorting for anything containing the locator for the given day.
  mask.to_csv(file2) ##I'm now updating file 2 so that it only has the data I want sorted for.
  data2 = pd.read_csv(file2,header='infer')
  df2=pd.DataFrame(data=data2)
  
  def tojuliandate(date):
     return.... ##give a function that changes normal date of format %Y%m%dT%H%M%SZ to julian date format of %y%j
  def timeofday(date):
      changes %Y%m%dT%H%M%SZ to %H%M%S for more narrow views of data
  
  df2['Time of Day'] = df2['DateTime'].apply(timeofday)
  df2.to_csv(file2) ##adds a column for "timeofday" to the file
  </code></pre>
  
  <p>So basically at this point this is all the code that goes into making the csv I want to sort. How would I go about sorting </p>
  
  <pre><code>'Zenith' and 'Azimuth' 
  </code></pre>
  
  <p>If they met the criteria I specified above?</p>
  
  <p>I know that I will need if statements to do this.
  I tried something like this but it didn't work and I was looking for a bit of help:</p>