Selectively Modify Elements of a Vector

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)
#> 'data.frame':	150 obs. of  5 variables:
#>  $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
#>  $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
#>  $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
#>  $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
#>  $ Species     : chr  "setosa" "setosa" "setosa" "setosa" ...

x = modify_at(iris, 5, as.character)
x = modify_at(iris, "Sepal.Length", sqrt)
str(x)
#> 'data.frame':	150 obs. of  5 variables:
#>  $ Sepal.Length: num  2.26 2.21 2.17 2.14 2.24 ...
#>  $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
#>  $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
#>  $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
#>  $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...