title: Iterating through dataframe using regular expression python
body: <p>I a trying parse SI type patterns in another column in a DF or in a list
  I tried 2 things:</p>
  
  <pre><code>|    a             |
  -------------------+
  | Builder          |
  | left             |
  | SI_NAME lide_on  |
  | SI_ID 456        |
  | Scheduling Info  |
  
  df['b']= df['a'].apply(lambda row: re.findall('\SI_\w+\s',row))  
  </code></pre>
  
  <p>and </p>
  
  <pre><code>list_DF=[]
  for index,row in df.iterrows():
      list_DF.append(re.findall('\SI_\w+\s',row[0]))
  </code></pre>
  
  <p>I am not able to get the result and the first one returned an empty list in the new column</p>