title: Select subset of Data Frame rows based on a list in Pandas
body: <p>I have a data frame <code>df1</code> and list <code>x</code>:</p>
  
  <pre><code>In [22] : import pandas as pd
  In [23]: df1 = pd.DataFrame({'C': range(5), "B":range(10,20,2), "A":list('abcde')})
  In [24]: df1
  Out[24]:
     A   B  C
  0  a  10  0
  1  b  12  1
  2  c  14  2
  3  d  16  3
  4  e  18  4
  
  In [25]: x = ["b","c","g","h","j"]
  </code></pre>
  
  <p>What I want to do is to select rows in data frame based on the list. 
  Returning </p>
  
  <pre><code>   A   B  C
  1  b  12  1
  2  c  14  2
  </code></pre>
  
  <p>What's the way to do it?
  I tried this but failed.</p>
  
  <pre><code>df1.join(pd.DataFrame(x),how="inner")
  </code></pre>