title: get column name that contains a specific value in pandas
body: <p>I want to get column name from the whole database (assume the database contains more than 100 rows with more than 50 column) based on specific value that contain in a specific column in pandas.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import pandas as pd
  df = pd.DataFrame({'A':[1,2,3], 'B':[4,5,6], 'C':[7,8,9]})
  pos = 2
  response = raw_input("input")
  placeholder = (df == response).idxmax(axis=1)[0]
  print df
  print (placeholder)
  </code></pre>
  
  <p>Tried a lot . . .</p>
  
  <p>Example:
  when the user will input 2; it will show answer: A
  if the input is 4; feedback will be B
  and if 7 then reply will be C</p>
  
  <p>tried iloc but I've seen row have to be noticed there.</p>
  
  <p>Please Help Dear Guys . . . . .
  Thanks . . . :)</p>