which_: Memory-efficient alternative to 'which()'

In cheapr: Simple Functions to Save Time and Memory

Memory-efficient alternative to which()

Description

Exactly the same as which() but more memory efficient.

Usage

which_(x, invert = FALSE)

Arguments

x	A logical vector.
invert	If TRUE, indices of values that are not TRUE are returned (including NA). If FALSE (the default), only TRUE indices are returned.

Details

This implementation is similar in speed to which() but usually more memory efficient.

Value

An unnamed integer vector.

Examples

library(cheapr)
library(bench)
x <- sample(c(TRUE, FALSE), 1e05, TRUE)
x[sample.int(1e05, round(1e05/3))] <- NA

mark(which_(TRUE), which(TRUE))
mark(which_(FALSE), which(FALSE))
mark(which_(logical()), which(logical()))
mark(which_(x), which(x), iterations = 20)
mark(base = which(is.na(match(x, TRUE))),
     collapse = collapse::whichv(x, TRUE, invert = TRUE),
     cheapr = which_(x, invert = TRUE),
     iterations = 20)

cheapr documentation built on June 8, 2025, 11:35 a.m.