vctrs: list_of – R documentation

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list_of

list_of S3 class for homogenous lists

Description

A list_of object is a list where each element has the same type. Modifying the list with $, [, and [[ preserves the constraint by coercing all input items.

Usage

list_of(..., .ptype = NULL)

as_list_of(x, ...)

validate_list_of(x)

is_list_of(x)

## S3 method for class 'vctrs_list_of'
vec_ptype2(x, y, ..., x_arg = "", y_arg = "")

## S3 method for class 'vctrs_list_of'
vec_cast(x, to, ...)

Arguments

`...`	Vectors to coerce.
`.ptype`	If `NULL`, the default, the output type is determined by computing the common type across all elements of `...`. Alternatively, you can supply `.ptype` to give the output known type. If `getOption("vctrs.no_guessing")` is `TRUE` you must supply this value: this is a convenient way to make production code demand fixed types.
`x`	For `as_list_of()`, a vector to be coerced to list_of.
`y, to`	Arguments to `vec_ptype2()` and `vec_cast()`.
`x_arg`	Argument names for `x` and `y`. These are used in error messages to inform the user about the locations of incompatible types (see `stop_incompatible_type()`).
`y_arg`	Argument names for `x` and `y`. These are used in error messages to inform the user about the locations of incompatible types (see `stop_incompatible_type()`).

Details

Unlike regular lists, setting a list element to NULL using [[ does not remove it.

Examples

x <- list_of(1:3, 5:6, 10:15)
if (requireNamespace("tibble", quietly = TRUE)) {
  tibble::tibble(x = x)
}

vec_c(list_of(1, 2), list_of(FALSE, TRUE))

vctrs

Vector Helpers

v0.3.8

MIT + file LICENSE

Authors

Hadley Wickham [aut], Lionel Henry [aut, cre], Davis Vaughan [aut], data.table team [cph] (Radix sort based on data.table's forder() and their contribution to R's order()), RStudio [cph]

Initial release