title: In Python Pandas, boolean operation
body: <p>I am performing boolean operation on two Series. I was expecting the boolean operation to automatically do the operation corresponding to the same index. But instead it just does it by order. Is this the expected behavior or there is some different way of doing this?
  Thanks</p>
  
  <pre><code>b
  Out[47]: 
  AEIS    False
  AAPL     True
  ACFN    False
  Name: OldPosition, dtype: bool
  
  a
  Out[48]: 
  AAPL     True
  ACFN    False
  AEIS     True
  dtype: bool
  
  a&amp;b
  Out[50]: 
  AAPL    False
  ACFN    False
  AEIS    False
  dtype: bool
  </code></pre>