title: TypeError: Could not compare <type 'str'> type with Series
body: <p>I get the following error when I try to filter a Dataframe by using a string   </p>
  
  <p><code>TypeError: Could not compare &lt;type 'str'&gt; type with Series</code></p>
  
  <p>This is my code;</p>
  
  <pre><code>data = pd.read_csv('data.csv')
  fildata = data[(data['cat1'] == 'FALSE') &amp; (data['cat2'] != '') &amp; (data['cat3'] == 'FALSE')]
  </code></pre>
  
  <p>EDIT 1:</p>
  
  <p>Here's how the data looks like;</p>
  
  <pre><code>count,word,cat1,cat2,cat3
  1021,.,FALSE,,FALSE
  825,the,TRUE,the,FALSE
  693,and,TRUE,and,FALSE
  647,of,TRUE,of,FALSE
  646,",",FALSE,,FALSE
  435,to,TRUE,to,FALSE
  353,will,TRUE,will,FALSE
  297,in,TRUE,in,FALSE
  274,be,TRUE,be,FALSE
  </code></pre>
  
  <p>EDIT 2:</p>
  
  <p>But why does this work?</p>
  
  <p><code>data1 = pd.DataFrame({'cat1':[1,2,3,4],'cat2':[2,3,1,4],'cat3':[3,1,2,4]})</code></p>
  
  <p><code>fildata = data1[(data1['cat1'] == 1) &amp; (data1['cat2'] != 0) &amp; (data1['cat3']== 3)]</code> </p>
  
  <p>This results in;</p>
  
  <p><code>cat1  cat2  cat3
  0     1     2     3</code></p>
  
  <p>EDIT 3:</p>
  
  <p>I guess the problem is with the type. 'cat1' &amp; 'cat2' are of the type <code>'bool'</code></p>