title: Select from pandas dataframe using boolean series/array
body: <p>I have a dataframe:</p>
  
  <pre><code>             High    Low  Close
  Date                           
  2009-02-11  30.20  29.41  29.87
  2009-02-12  30.28  29.32  30.24
  2009-02-13  30.45  29.96  30.10
  2009-02-17  29.35  28.74  28.90
  2009-02-18  29.35  28.56  28.92
  </code></pre>
  
  <p>and a boolean series:</p>
  
  <pre><code>     bools
  1    True
  2    False
  3    False
  4    True
  5    False
  </code></pre>
  
  <p>how could I select from the dataframe using the boolean array to obtain result like:</p>
  
  <pre><code>             High   
  Date                           
  2009-02-11  30.20  
  2009-02-17  29.35  
  </code></pre>