Convert matrix to 3-column table ('reverse pivot', 'unpivot', 'flatten', 'normalize')

Question

I need to convert the Excel matrix FIRST in the table LATER:

FIRST:

    P1  P2  P3  P4
F1  X
F2  X   X
F3      X       X
F4      X   X

LATER:

F   P   VALUE
F1  P1  X
F1  P2
F1  P3
F1  P4
F2  P1  X
F2  P2  X
F2  P3
F2  P4
F3  P1
F3  P2  X
F3  P3
F3  P4  X
F4  P1
F4  P2  X
F4  P3  X
F4  P4

Answer 1

Another way to unpivot data without using VBA is with PowerQuery, a free add-in for Excel 2010 and higher, available here: http://www.microsoft.com/en-us/download/details.aspx?id=39379

Install and activate the Power Query add-in. Then follow these steps:

Add a column label to your data source and turn it into an Excel Table via Insert > Table or Ctrl - T.

Select any cell in the table and on the Power Query ribbon click "From Table".

This will open the table in the Power Query Editor window.

Click the column header of the first column to select it. Then, on the Transform ribbon, click the Unpivot Columns drop-down and select Unpivot other columns.

For versions of Power Query that don't have the Unpivot other columns command, select all columns except the first one (using Shift-click on the column headers) and use the Unpivot command.

The result is a flat table. Click Close and Load on the Home ribbon and the data will be loaded onto a new Excel sheet.

Now to the good part. Add some data to your source table, for example

Click on the sheet with the Power Query result table and on the Data ribbon click Refresh all. You will see something like:

Power Query is not just a one-time transformation. It is repeatable and can be linked to dynamically changing data.

Answer 2

All of the solutions so far involve VBA, PowerQuery, etc. which are great, but are "one-time" events. To make it more dynamic, consider using INDEX(MATCH(...)). This will allow for dynamic updates to the table.

Answer 3

The addition of the LET function & dynamic arrays allows for this non-VBA solution.

=LET(data,B2:E5,
     dataRows,ROWS(data),
     dataCols,COLUMNS(data),
     rowHeaders,OFFSET(data,0,-1,dataRows,1),
     colHeaders,OFFSET(data,-1,0,1,dataCols),
     dataIndex,SEQUENCE(dataRows*dataCols),
     rowIndex,MOD(dataIndex-1,dataRows)+1,
     colIndex,INT((dataIndex-1)/dataRows)+1,
     dataColumn, IF(INDEX(data,rowIndex,colIndex)="","",INDEX(data,rowIndex,colIndex)),
     unfiltered, CHOOSE({1,2,3},INDEX(rowHeaders,rowIndex),INDEX(colHeaders,colIndex), dataColumn),
     filtered, FILTER(unfiltered, dataColumn<>""),
     unfiltered)

This will show all items including those with blank data. To eliminate the blanks change the last parameter to filtered.

Answer 4

One more to add to the BoK. This requires Excel 365. It unpivots B1:E5 by A1:A5.

=LET( unPivMatrix, B1:E5,
      byMatrix, A1:A5,
        upC, COLUMNS( unPivMatrix ),
        byC, COLUMNS( byMatrix ),
        dmxR, MIN( ROWS( unPivMatrix ), ROWS( byMatrix ) ) - 1,
        dmxSeq, SEQUENCE( dmxR ) + 1,
        upCells, dmxR * upC,
        upSeq, SEQUENCE( upCells,, 0 ),
        upHdr, INDEX( INDEX( unPivMatrix, 1, ),  1,  SEQUENCE( upC ) ),
        upBody, INDEX( unPivMatrix,  dmxSeq,  SEQUENCE( 1, upC ) ),
        byBody, INDEX( byMatrix,  dmxSeq,  SEQUENCE( 1, byC ) ),
        attr, INDEX( upHdr, MOD( upSeq, upC ) + 1 ),
        mux, INDEX( upBody, upSeq/upC + 1, MOD( upSeq, upC ) + 1 ),
        demux, IFERROR( INDEX(
                              IFERROR( INDEX( byBody,
                                              IFERROR( INT( SEQUENCE( upCells, byC,0 )/byC/upC ) + 1, MOD( upSeq, upC ) + 1 ),
                                                       SEQUENCE( 1, byC + 1 ) ),
                                        attr ),
                              upSeq + 1, SEQUENCE( 1, byC + 2 ) ),
                         mux ),
        FILTER(demux, mux<>"")
 )

NB: the byMatrix can be a range with multiple columns and it will replicate the row values of the columns. e.g. you could have byMatrix of A1:C5 and unPivMatrix of D1:H5 and it would replicate the A2:C5 column values (ignoring A1).