title: How do I groupby one column in a dataframe and combine on another column no matter if there is text or blanks?
body: <p>I want to <code>groupby</code> on one column of a <code>Dataframe</code> and then combine any text in another column for the unique values of the first column (call_ID). The code should also delete any duplicates. My problem seems to be in deleting the duplicates. I tried the code below but it is not successful.</p>
  <pre><code># Dataframe
  dftest0 = pd.DataFrame(data ={'call_ID':[5423684,5423684,5423684,5423684],
  'other_comb_words':['','','inspection','inspection']})
  
  # Change datatype
  dftest0['call_ID'] = dftest0['call_ID'].astype(str)
  
  # groupby and combine text
  dftest0['other_comb_words'] = dftest0.groupby(['call_ID'], as_index=False)
  ['other_comb_words'].transform(lambda x : ' '.join(x))
  
  # remove duplicates
  dftest0 = dftest0.drop_duplicates(subset='other_comb_words')  
  dftest0
  </code></pre>
  <p><code>Dataframe</code> sample:</p>
  <pre><code>call_ID other_comb_words
  5423684 
  5423684 
  5423684 inspection
  5423684 inspection
  </code></pre>
  <p>Current output:</p>
  <pre><code>call_ID other_comb_words
  5423684 inspection inspection
  </code></pre>
  <p>Desired output:</p>
  <pre><code>call_ID other_comb_words
  5423684 inspection
  </code></pre>