UNPIVOT GS

gistfile1.txt

/**
 * Unpivot a pivot table of any size.
 *
 * @param {A1:D30} data The pivot table.
 * @param {1} fixColumns Number of columns, after which pivoted values begin. Default 1.
 * @param {1} fixRows Number of rows (1 or 2), after which pivoted values begin. Default 1.
 * @param {"city"} titlePivot The title of horizontal pivot values. Default "column".
 * @param {"distance"[,...]} titleValue The title of pivot table values. Default "value".
 * @return The unpivoted table
 * @customfunction
 */
function unpivot(data,fixColumns,fixRows,titlePivot,titleValue) {  
  var fixColumns = fixColumns || 1; // how many columns are fixed
  var fixRows = fixRows || 1; // how many rows are fixed
  var titlePivot = titlePivot || 'column';
  var titleValue = titleValue || 'value';
  var ret=[],i,j,row,uniqueCols=1;
  
  // we handle only 2 dimension arrays
  if (!Array.isArray(data) || data.length < fixRows || !Array.isArray(data[0]) || data[0].length < fixColumns)
    throw new Error('no data');
  // we handle max 2 fixed rows
  if (fixRows > 2)
    throw new Error('max 2 fixed rows are allowed');
  
  // fill empty cells in the first row with value set last in previous columns (for 2 fixed rows)
  var tmp = '';
  for (j=0;j<data[0].length;j++)
    if (data[0][j] != '') 
      tmp = data[0][j];
    else
      data[0][j] = tmp;
  
  // for 2 fixed rows calculate unique column number
  if (fixRows == 2)
  {
    uniqueCols = 0;
    tmp = {};
    for (j=fixColumns;j<data[1].length;j++)
      if (typeof tmp[ data[1][j] ] == 'undefined')
      {
        tmp[ data[1][j] ] = 1;
        uniqueCols++;
      }
  }
  
  // return first row: fix column titles + pivoted values column title + values column title(s)
  row = [];
    for (j=0;j<fixColumns;j++) row.push(fixRows == 2 ? data[0][j]||data[1][j] : data[0][j]); // for 2 fixed rows we try to find the title in row 1 and row 2
    for (j=3;j<arguments.length;j++) row.push(arguments[j]);
  ret.push(row);
    
  // processing rows (skipping the fixed columns, then dedicating a new row for each pivoted value)
  for (i=fixRows;i<data.length && data[i].length > 0;i++)
  {
    // skip totally empty or only whitespace containing rows
    if (data[i].join('').replace(/\s+/g,'').length == 0 ) continue;
    
    // unpivot the row
    row = [];
    for (j=0;j<fixColumns && j<data[i].length;j++)
      row.push(data[i][j]);
    for (j=fixColumns;j<data[i].length;j+=uniqueCols)
      ret.push( 
        row.concat([data[0][j]]) // the first row title value
        .concat(data[i].slice(j,j+uniqueCols)) // pivoted values
      );
  }

  return ret;
}

Hello,

With the two rows of headers setup, the functions was not exactly doing what I wanted.
Here is what I am trying to achieve :

In order to do that I modified your version. Here is the forked gist :
https://gist.github.com/bactisme/fbb1fd1c19a9f78e5f15fc7e218a4904

Thanks again.

By the way, Google Sheets has an undocumented function called FLATTEN() which can be used to unpivot wide data much like this script can. I've used it and it works quite well. Instructions are floating around the web and are not too hard to find.

Thank you for sharing! It was exactly what I needed!

I encountered "Too large data" error when I run this script, any ideas how I can get around that?

Perfect! Huge help.
Thanks!

If you have csv like

Name, cat 1, cat 2, cat 3, cat 4

and you want to flatten it for look up purpopses

you wil have to UNPIVOT

to do so..

make the data do the following

Name,Name,Name,Name,cat 1, cat 2, cat 3, cat 4

Then Flatten the first 4 columns

and then next to it flatten the next 4 columns,

it should alone

Name,Cat 1
Name, Cat 2
Name, Cat 3,
Name, Cat 4

Right?