title: Pandas : how to add Column name on dataframe on csv file
body: <p>new but excited about Python and i need your advice. I came up with the following code to compare two CSV files based on nmap scan:</p>
  
  <pre><code>import pandas as pd
  from pandas import DataFrame
  import os
  file = raw_input('\nEnter the Old CSV file: ')
  file1 = raw_input('\nEnter the New CSV file: ')
  A=set(pd.read_csv(file, index_col=False, header=None)[0])
  B=set(pd.read_csv(file1, index_col=False, header=None)[0])
  final=list(A-B)
  df = pd.DataFrame(final, columns=["host"])
  df.to_csv('DIFF_'+file)
  
  print "Completed!"
  </code></pre>
  
  <p>when i run it i got the following results:
  ,</p>
  
  <pre><code>host
  0,82.214.228.71;dsl-radius-02.direcpceu.com;PTR;tcp;111;rpcbind;open;;;syn-ack;;3;
  1,82.214.228.70;dsl-radius-01.direcpceu.com;PTR;tcp;111;rpcbind;open;;;syn-ack;;3;
  </code></pre>
  
  <p>My question is how to add a label/<code>enter code here</code>name on the columns 2,3 etc for example: hostanme , port , port name ,state etc.
  I have tried :
  df['hostname'] = range(1, len(df) + 1) but this adds the hostname on the first column along with host when i open the file with Excel</p>