title: Pandas dataframe slice indexing by index criterias
body: <p>I often need to do some searching in the index by some higher/lower than criteria in Pandas DataFrame.
  I have found a way to do it, but it feels a bit cumbersome, or somehow unsmart.
  This is my current method:</p>
  
  <pre><code>from numpy import linspace
  import pandas as pd
  
  df = pd.DataFrame(linspace(1,5,5),index=linspace(0.1,0.5,5))
  
  df
  
       0
  0.1  1
  0.2  2
  0.3  3
  0.4  4
  0.5  5
  
  df[(df.index&gt;0.3) * (df.index &lt;0.5)]
  
       0
  0.3  3
  0.4  4
  </code></pre>
  
  <p>It does give me what I wan't, but please suggest a better way if you have one.</p>