title: Data frame with unique values from other data frame(pandas, python)
body: <p>I have data frame in which I have duplicates values (in each column not duplicated rows).
  Data look like that:</p>
  
  <pre><code>|Col1|Col2|Cold3|Col4|
  |   1|   A| John| -10|
  |   2|   A|Scoot| 234|
  |   2|   B|Kerry| 346|
  |   6|   B| Adam| -10|
  </code></pre>
  
  <p>I would like to create another df from this one which would look like that:</p>
  
  <pre><code>|Col1|Col2|Cold3|Col4|
  |   1|   A| John| -10|
  |   2|   B|Scoot| 234|
  |   6|null|Kerry| 346|
  |null|null| Adam|null|
  </code></pre>
  
  <p>Those null could be NaN of course.</p>
  
  <p>I can go by each column and print unique values for each:</p>
  
  <pre><code>for col in df:
      print (df[col].unique())
  </code></pre>
  
  <p>which returns numpy arrays.
  But I'm not sure how to write it to new data frame to look like one that I showed erlier.</p>