Reorganised a long format table to a wide data table

GibbE155 

Since you said "hundreds of thousands", I recommend you don't use formulas for this, but instead use Power Query.

Select any cell in your data and use Data>Get & Transform Data>From Table/Range

This will open the Power Query Editor.

Now, use Add Column>General>Custom Column and use this formula:

"Sample " & Number.ToText([Sample])

Call the new column ColumnHeader (not essential, you can call it whatever you want).

Now right-click the Sample column and select Remove.

Next, select the ColumnHeader column you created above and use Home>Transform>Group By and configure the dialog like this:

Now use Add Column>General>Custom Column with this formula:

Table.AddIndexColumn([GroupIndex], "Index", 1, 1)

I called this new custom column DataWithGroupIndex.

Now I have three columns:

Right-click GroupIndex and Remove that column, then click the double-arrow in the top right hand corner of the DataWithGroupIndex column to expand the data that currently says "Table".

In the expand field dialog, I've configured it like this:

I know this seems like a lot of steps, but once done, this process will be repeatable and you won't be sat waiting for 7 hundreds of thousands of formulas to recalculate.

The point of the steps leading up to here was to get an index column that repeats when the column header changes, which will be important for the next step.

Now select the ColumnHeader column and use Transform>Any Column>Pivot Column and configure it like this:

After clicking OK, you'll see that the data are properly top-loaded into each Sample column.

You can right-click the Index and Remove it, then use Home>Close & Load to put the results back into the workbook.

If you want, you can just open the attached workbook, select any cell in the green table, go to the Query Tab, select Edit, then on the Home Tab of the Power Query Editor, click Advanced Editor to see the code for the whole query, which you should be able to put into your own workbook with some minimal editing if you're comfortable with that.