GroupBy[{{a, 1, x}, {b, 2, v}, {a, 3, y}, {a, 7, z}, {b, 2, w}}, First -> Last, Total]
adds the last element or last element. How can I add the second element?
Do you mean just the second elements instead of the last elements?
GroupBy[{{a, 1, x}, {b, 2, v}, {a, 3, y}, {a, 7, z}, {b, 2, w}}, First -> (#[[2]] &), Total] (* <|a -> 11, b -> 4|> *)
Thank you very much Eric!!!
