title: Python pandas -> select by condition in columns name
body: <p>I have df with column names: 'a', 'b', 'c' ... 'z'.</p>
  
  <pre><code>print(my_df.columns)
  Index(['a', 'b', 'c', ... 'y', 'z'],
    dtype='object', name=0)
  </code></pre>
  
  <p>I have function which determine which columns should be displayed. For example:</p>
  
  <pre><code>start = con_start()
  stop = con_stop()
  print(my_df.columns &gt;= start) &amp; (my_df &lt;= stop)
  </code></pre>
  
  <p>My result is:</p>
  
  <pre><code>[False False ... False False False False  True  True
  True  True False False]
  </code></pre>
  
  <p>My goal is display dataframe only with columns that satisfy my condition.
  If start = 'a' and stop = 'b', I want to have:</p>
  
  <pre><code>0                                      a              b         
  index1       index2                                                  
  New York     New York           0.000000       0.000000          
  California   Los Angeles   207066.666667  214466.666667     
  Illinois     Chicago       138400.000000  143633.333333     
  Pennsylvania Philadelphia   53000.000000   53633.333333      
  Arizona      Phoenix       111833.333333  114366.666667 
  </code></pre>