Google-sheets – Array formula (or other) to copy down formula in adjacent cell to last row with data

I had a similar problem. sheetSpider does not appear to be available anymore. I tried writing my own script and it kinda worked but it was slow and didn't update reliably when the source data changed.

I eventually solved my problem with a pivot table (Data->Pivot table report...). Just select the range, then add all the columns you want to see as Rows (sounds counterintuitive I know) and set Filters for Column B > 1 and Column D = teacher's name. Create a new pivot table for each teacher on its own sheet where the second filter varies. More details about pivot tables in Google Sheets here. For me it is quick and updates well whenever the source data changes.

Instead of getFormulas and setFormulas, use copyTo method:

range.copyTo(newRange);

This will have the same effect as if you selected the last row and copied it below. In particular, it will also copy down any values that were entered directly into cells. If you prefer such values to not be copied, use getFormulas/setFormulas combination on newRange:

range.copyTo(newRange);
newRange.setFormulas(newRange.getFormulas());

The effect of the last line: no change of formulas, but the cells that didn't contain a formula will become empty.

R1C1 approach

You can also try replacing the last three rows of addRow with

var formulas = range.getFormulasR1C1();
var newRange = sh.getRange(lRow+1,1,1,lCol);
newRange.setFormulasR1C1(formulas);

This will make sure the references in formulas are remapped as if you copy-pasted them. However, this has a major limitation: setFormulasR1C1 doesn't work correctly with empty string as its argument, which will result in #ERROR! messages in the cells that should be left blank.

The reason R1C1 works differently is that getFormulasR1C1 retrieves formulas in a relative form: for example, a reference from A3 to D2 becomes R[-1]C[3], meaning "one row up, three columns to the right". When the formula is set to, for example, E4 with setFormulasR1C1, the cell reference will appear as H3.