arrayformula sum in Google spreadsheet

Question

How do you arrayformula() a sum() such as:

=sum(A1:H1)

I need to go down 1000 rows.

Answer 1

if I look at this formula I really think the following might be simpler. Add this to Tools > Script Editor:

function row_sum(range_to_sum_per_row) {
  var result_column = [];
  for (var r = 0; r < range_to_sum_per_row.length; r++) {
    var row_sum = parseFloat(0);
    for (var c = 0; c < range_to_sum_per_row[r].length; c++) {
        row_sum += range_to_sum_per_row[r][c] || 0;
    }
    result_column.push([row_sum]);
  }
  return result_column;
}

use this like so for performance reasons, where C:H is the range you want to sum up and A:A is a column that does not contain an empty string:

=row_sum(filter(C2:H, len(A2:A)>0))