analytics (version 3.0)

colsum: Give Row sums of a Matrix-like Object, Based on a Grouping Variable

Description

Compute Row sums across columns of a numeric matrix-like object for each level of a grouping variable.

Usage

colsum(M, group = colnames(M), reord = FALSE, na_rm = FALSE,
  big = TRUE, ...)

Arguments

M

a matrix, data frame or vector of numeric data. Missing values are allowed. A numeric vector will be treated as a column vector.

group

a vector or factor giving the grouping, with one element per row of M. Default: rownames of M.

reord

if TRUE, then the result will be in order of sort(unique(group)), if FALSE (the default), it will be in the order that groups were encountered.

na_rm

logical (TRUE or FALSE). Should NA (including NaN) values be discarded?

big

is your object big and integer overflow is likely? If TRUE, then M is multiplied by 1.0 to ensure values are of type double (perhaps taking more RAM).

...

other arguments to be passed to or from methods.

Value

A matrix-like object containing the sums by group. There will be one row per unique value of group.

Details

This function is a wrapper for base function rowsum and is its "column" version.

See Also

rowsum

Examples

# NOT RUN {
A <- matrix(1:8, ncol = 4)
colnames(A) <- c("A", "B", "A", "B")
colsum(A)

# }