title: How to use dataframe one column to match dict values to get the dict key
body: <p>I have a dataframe with a column having company names:
  such as</p>
  <pre><code>ID  NAME     dict_key
  1   APPLE      NaN
  2   GOOGLE     Nan
  3   IBM        NaN
  4   HP         NaN
  5   SAMSUNG    NaN
  </code></pre>
  <p>...</p>
  <p>And i have a dict key and multiple values for corresponding keys, such as</p>
  <pre><code>{1000:['APPLE INC', 'APPLE COMPUTER INC', 'AOPLE INC', 'APPLE'], 1001:['GOOGLE INC', 'GOOGLE','GOOLELL INC']}.....
  </code></pre>
  <p>I want to write a loop to see if dataframe second column company names in the dictionary, if they are matched, like APPLE in first row and first column going to match APPLE in dict with key 1000, then I want to  assign the key to dict_key column.
  Thanks a lot.</p>