R: Selectively Modify Elements of a Vector

modify_if {mlr3misc} | R Documentation

## Selectively Modify Elements of a Vector

### Description

Modifies elements of a vector selectively, similar to the functions in purrr.

`modify_if()` applies a predicate function `.p` to all elements of `.x` and applies `.f` to those elements of `.x` where `.p` evaluates to `TRUE`.

`modify_at()` applies `.f` to those elements of `.x` selected via `.at`.

### Usage

    modify_if(.x, .p, .f, ...)

    modify_at(.x, .at, .f, ...)

### Arguments

`.x` | (`vector()`).
`.p` | (`function()`) Predicate function.
`.f` | (`function()`) Function to apply on `.x`.
`...` | (`any`) Additional arguments passed to `.f`.
`.at` | ((`integer()` | `character()`)) Index vector to select elements from `.x`.

### Examples

    x = modify_if(iris, is.factor, as.character)
    str(x)

    x = modify_at(iris, 5, as.character)
    x = modify_at(iris, "Sepal.Length", sqrt)
    str(x)

[Package mlr3misc version 0.9.2 Index]