Compute per-group sums

sum_g(col, first_indices, na.rm = FALSE)

Arguments

col	vector to sum
first_indices	numeric index of first index in each group
na.rm	locial if TRUE remove NAs

per-group sum


v <- c(2, 3, 1, NA, 5)
fi <- c(1, 1, 3, 3, 3)
sum_g(v, fi)
#> [1]  5  5 NA NA NA