Exactly rounded row, column and grouped sums

xsum_rowsums() and xsum_colsums() are exact versions of rowSums() and colSums(): every row or column sum is the correctly rounded exact sum. xsum_by() is an exact version of rowsum(): the rows of x are summed within each group, and the result has one row per group, sorted.

Usage

xsum_rowsums(x, na.rm = FALSE)

xsum_colsums(x, na.rm = FALSE)

xsum_by(x, group, na.rm = FALSE)

Arguments

x: A numeric or logical matrix, or a data frame of numeric or logical columns. For xsum_by(), also a vector.
na.rm: Remove NA and NaN values before summing?
group: A vector with one value per row of x (per element, for a vector). NA is a group of its own, sorted last, as in rowsum().

Value

xsum_rowsums() and xsum_colsums() return a double vector named by the row or column names. xsum_by() returns a double matrix with one row per group (named by the group) and one column per column of x.

Details

Special values follow the table in xsum(), cell by cell. Row sums are computed a block of rows at a time, so the extra memory they need does not grow with the number of rows.

Examples

m <- cbind(a = c(1e20, 1), b = c(1, 1e20), c = c(-1e20, -1e20))
rowSums(m)
#> [1] 0 0
xsum_rowsums(m)
#> [1] 1 1
xsum_colsums(m)
#>      a      b      c 
#>  1e+20  1e+20 -2e+20 

xsum_by(c(1e20, 1, 2, -1e20), c("x", "y", "y", "x"))
#>   [,1]
#> x    0
#> y    3