title: Unmelt only part of a column from pandas dataframe
body: <p>I have the following example dataframe:</p>
  
  <pre class="lang-py prettyprint-override"><code>df = pd.DataFrame(data = {'RecordID' : [1,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5], 'DisplayLabel' : ['Source','Test','Value 1','Value 2','Value3','Source','Test','Value 1','Value 2','Source','Test','Value 1','Value 2','Source','Test','Value 1','Value 2','Source','Test','Value 1','Value 2'],
  'Value' : ['Web','Logic','S','I','Complete','Person','Voice','&gt;20','P','Mail','OCR','A','I','Dictation','Understandable','S','I','Web','Logic','R','S']})
  </code></pre>
  
  <p>which creates this dataframe:</p>
  
  <pre><code>+-------+----------+---------------+----------------+
  | Index | RecordID | Display Label |     Value      |
  +-------+----------+---------------+----------------+
  |     0 |        1 | Source        | Web            |
  |     1 |        1 | Test          | Logic          |
  |     2 |        1 | Value 1       | S              |
  |     3 |        1 | Value 2       | I              |
  |     4 |        1 | Value 3       | Complete       |
  |     5 |        2 | Source        | Person         |
  |     6 |        2 | Test          | Voice          |
  |     7 |        2 | Value 1       | &gt;20            |
  |     8 |        2 | Value 2       | P              |
  |     9 |        3 | Source        | Mail           |
  |    10 |        3 | Test          | OCR            |
  |    11 |        3 | Value 1       | A              |
  |    12 |        3 | Value 2       | I              |
  |    13 |        4 | Source        | Dictation      |
  |    14 |        4 | Test          | Understandable |
  |    15 |        4 | Value 1       | S              |
  |    16 |        4 | Value 2       | I              |
  |    17 |        5 | Source        | Web            |
  |    18 |        5 | Test          | Logic          |
  |    19 |        5 | Value 1       | R              |
  |    20 |        5 | Value 2       | S              |
  +-------+----------+---------------+----------------+
  </code></pre>
  
  <p>I am trying to "unmelt" though not exactly the source and test columns into new dataframe Columns such that it will look like this:</p>
  
  <pre><code>+-------+----------+-----------+----------------+---------------+----------+
  | Index | RecordID |  Source   |      Test      | Result        |  Value   |
  +-------+----------+-----------+----------------+---------------+----------+
  |     0 |        1 | Web       | Logic          | Value 1       | S        |
  |     1 |        1 | Web       | Logic          | Value 2       | I        |
  |     2 |        1 | Web       | Logic          | Value 3       | Complete |
  |     3 |        2 | Person    | Voice          | Value 1       | &gt;20      |
  |     4 |        2 | Person    | Voice          | Value 2       | P        |
  |     5 |        3 | Mail      | OCR            | Value 1       | A        |
  |     6 |        3 | Mail      | OCR            | Value 2       | I        |
  |     7 |        4 | Dictation | Understandable | Value 1       | S        |
  |     8 |        4 | Dictation | Understandable | Value 2       | I        |
  |     9 |        5 | Web       | Logic          | Value 1       | R        |
  |    10 |        5 | Web       | Logic          | Value 2       | S        |
  +-------+----------+-----------+----------------+---------------+----------+
  </code></pre>
  
  <p>It's my understanding that pivot and melt will do the entire DisplayLabel column and not just some of the values.</p>
  
  <p>Any help would be greatly appreciated as I have read the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.melt.html" rel="noreferrer">Pandas Melt</a> and the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.pivot.html#pandas.pivot" rel="noreferrer">Pandas Pivot</a>  as well as some references on stackoverflow and I can't seem to figure out a way to do this quickly.</p>
  
  <p>Thanks!</p>