ffbase (version 0.13.3)

bySum: Fast conditional sum

Description

bySum works like a very fast version of tapply with (weighted) FUN=sum.

Usage

bySum(x, by, na.rm = FALSE, weight = NULL, ...)

Arguments

x

numeric vector to be summed

by

(list of) factor(s) for which the sum will be calculated

na.rm

logical If TRUE NA values will be removed

weight

numeric with of same length as x

...

not used

Value

array with dimensions of by

Examples

# NOT RUN {
bySum(warpbreaks$breaks, warpbreaks$wool)
bySum(warpbreaks$breaks, warpbreaks[,-1])
# }