transform_if: transform_if: Conditional Sub-set Transformation of Atomic...
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transform_if

R Documentation

transform_if: Conditional Sub-set Transformation of Atomic objects

Description

The transform_if() function transforms an object x, based on the logical result (TRUE, FALSE, NA) of condition function cond(x) or logical vector cond, such that:

For every value where cond(x)==TRUE / cond==TRUE, function yes(x) is run or scalar yes is returned.
For every value where cond(x)==FALSE / cond==FALSE, function no(x) is run or scalar no is returned.
For every value where cond(x)==NA / cond==NA, function other(x) is run or scalar other is returned.

For a more ifelse-like function where yes, no, and other are vectors, see kit::iif.

Usage

transform_if(x, cond, yes = function(x) x, no = function(x) x, other = NA)

Arguments

`x`	a vector, matrix, or array.
`cond`	either an object of class `logical` with the same length as `x`, or a (possibly anonymous) function that returns an object of class `logical` with the same length as `x`. For example: `\(x)x>0`.
`yes`	the (possibly anonymous) transformation function to use when function `cond(x)==TRUE` / logical `cond==TRUE`. Alternatively, one can also supply an atomic scalar. If argument `yes` is not specified, it defaults to `\(x)x`.
`no`	the (possibly anonymous) transformation function to use when function `cond(x)==FALSE` / logical `cond==FALSE`. Alternatively, one can also supply an atomic scalar. If argument `no` is not specified, it defaults to `\(x)x`.
`other`	the (possibly anonymous) transformation function to use when function `cond(x)` / logical `cond` returns `NA`. Alternatively, one can also supply an atomic scalar. If argument `other` is not specified, it defaults to `NA`. Note that function `other(x)` is run or scalar `other` is returned when function `cond(x)` or logical `cond` is `NA`, not necessarily when `x` itself is `NA`.

Details

Be careful with coercion! For example the following code:

x <- c("a", "b")
transform_if(x, \(x) x == "a", as.numeric, as.logical)

returns:

[1] NA NA

due to the same character vector being given 2 incompatible classes.

Value

The transformed vector, matrix, or array (attributes are conserved).

Examples

x <- c(-10:9, NA, NA)
object <- matrix(x, ncol = 2)
attr(object, "helloworld") <- "helloworld"
print(object)
y <- 0
z <- 1000

object |> transform_if(\(x) x > y, log, \(x) x^2, \(x) -z)
object |> transform_if(object > y, log, \(x) x^2, -z) # same as previous line

tinycodet documentation built on April 12, 2025, 1:39 a.m.