title: What happens when you compare 2 pandas Series
body: <p>I ran up against unexpected behavior in pandas when comparing two series.  I wanted to know if this is intended or a bug.</p>
  
  <p>suppose I:</p>
  
  <pre><code>import pandas as pd
  x = pd.Series([1, 1, 1, 0, 0, 0], index=['a', 'b', 'c', 'd', 'e', 'f'], name='Value')
  y = pd.Series([0, 2, 0, 2, 0, 2], index=['c', 'f', 'a', 'e', 'b', 'd'], name='Value')
  
  x &gt; y
  </code></pre>
  
  <p>yields:</p>
  
  <pre><code>a     True
  b    False
  c     True
  d    False
  e    False
  f    False
  Name: Value, dtype: bool
  </code></pre>
  
  <p>which isn't what I wanted.  Clearly, I expected the indexes to line up.  But I have to explicitly line them up to get the desired results.</p>
  
  <pre><code>x &gt; y.reindex_like(x)
  </code></pre>
  
  <p>yields:</p>
  
  <pre><code>a     True
  b     True
  c     True
  d    False
  e    False
  f    False
  Name: Value, dtype: bool
  </code></pre>
  
  <p>Which is what I expected.</p>
  
  <p>What's worse is if I:</p>
  
  <pre><code>x + y
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>a    1
  b    1
  c    1
  d    2
  e    2
  f    2
  Name: Value, dtype: int64
  </code></pre>
  
  <p>So when operating, the indexes line up.  When comparing, they do not.  Is my observation accurate?  Is this intended for some purpose?</p>
  
  <p>Thanks,</p>
  
  <p>-PiR</p>