purrr (version 0.2.2)

as_function: Convert an object into a function.

Description

as_function is the powerhouse behind the varied function specifications that purrr functions allow. This is an S3 generic so that other people can make as_function work with their own objects.

Usage

as_function(.f, ...)
"as_function"(.f, ..., .null = NULL)

Arguments

.f

A function, formula, or atomic vector.

If a function, it is used as is.

If a formula, e.g. ~ .x + 2, it is converted to a function with two arguments, .x or . and .y. This allows you to create very compact anonymous functions with up to two inputs.

If character or integer vector, e.g. "y", it is converted to an extractor function, function(x) x[["y"]]. To index deeply into a nested list, use multiple values; c("x", "y") is equivalent to z[["x"]][["y"]]. You can also set .null to set a default to use instead of NULL for absent components.

...

Additional arguments passed on to methods.

.null

Optional additional argument for character and numeric inputs.

Examples

as_function(~ . + 1)
as_function(1)
as_function(c("a", "b", "c"))
as_function(c("a", "b", "c"), .null = NA)

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