title: How do I merge column values from one dataframe to another if they are not present in another using pandas
body: <p>I have two different excel files which I read using <code>pd.readExcel</code>. The first excel file is kind of a master file which has a lot of columns. showing only those columns which are relevant:
  df1</p>
  <pre><code>Company Name                                              Excel Company ID
  0                                    cleverbridge AG      IQ109133656
  1  BT España, Compañía de Servicios Globales de T...        IQ3806173
  2                                   Technoserv Group       IQ40333012
  3                                    Blue Media S.A.       IQ50008102
  4            zeb.rolfes.schierenbeck.associates gmbh       IQ30413992
  </code></pre>
  <p>and the second excel is basically an output excel file which looks like this:
  df2</p>
  <pre><code>company_id          found_keywords  no_of_url                                       company_name
  0  IQ137156215      insurance         15                         Zühlke Technology Group AG
  1    IQ3806173      insurance         15  BT España, Compañía de Servicios Globales de T...
  2   IQ40333012      insurance          4                                   Technoserv Group
  3   IQ51614192      insurance         15                             Octo Telematics S.p.A.
  </code></pre>
  <p>I want this output excel file/ df2 to include those company_id and company name from df1 where company id and company name from df1 is not a part of df2. Something like this:
  df2</p>
  <pre><code>company_id found_keywords  no_of_url                                       company_name
  0  IQ137156215      insurance         15                         Zühlke Technology Group AG
  1    IQ3806173      insurance         15  BT España, Compañía de Servicios Globales de T...
  2   IQ40333012      insurance          4                                   Technoserv Group
  3   IQ51614192      insurance         15                             Octo Telematics S.p.A.
  4   IQ30413992      NaN               NaN              zeb.rolfes.schierenbeck.associates gmbh          
  </code></pre>
  <p>I tried several ways of achieveing this by using <code>pd.merge</code> as well as <code>np.where</code>
  I even tried reindexing based on columns but nothing worked out. What exactly do I need to do so that it works as expected. Please help me out.Thanks!</p>
  <p><strong>EDIT</strong>:</p>
  <p>using pd.merge</p>
  <pre><code>df2.merge(df, right_on='company_id', left_on='Excel Company ID', how='outer')
  </code></pre>
  <p>which gave an output with [220 rows X 31 columns]</p>