title: Python Pandas: Lookup table by searching for substring
body: <p>I have a dataframe with a column for app user-agents. What I need to do is to identify the particular app from this column. For example, </p>
  
  <p><code>NewWordsWithFriendsFree/2.3 CFNetwork/672.1.15 Darwin/14.0.0</code> will be categorized in <code>Words With Friends</code>. </p>
  
  <pre><code>iPhone3,1; iPhone OS 7.1.2; com.fingerarts.sudoku2; 143441-1,24 will be Sudoku by FingerArts etc.
  </code></pre>
  
  <p>I will have another dataframe with the strings I need to match. For example,</p>
  
  <pre><code>Keyword                 Game 
  NewWordsWithFriends     Words With Friends
  com.fingerarts.sudoku   Sudoku by FingerArts
  </code></pre>
  
  <p>How do I do the lookup like this for a pandas dataframe? The dataframe for example is like</p>
  
  <pre><code>user    date                 user-agent
   A      2015-09-02 13:45:56  NewWordsWithFriendsFree/2.3 CFNetwork/672.1.15 Darwin/14.0.0
   B      2015-08-31 23:04:21  iPhone3,1; iPhone OS 7.1.2; com.fingerarts.sudoku2; 143441-1,24
  </code></pre>
  
  <p>I want a new column <code>GameName</code> after the lookup.</p>