map: Apply function to elements in list

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Apply function to elements in list

Description

map applies a function to lists of arguments, similar to Map in base R, with the argument USE.NAMES set to FALSE. flatmap performs a recursive map: the return type is always a vector of some type given by the .default, and if the return value of calling .f is a vector, it is flattened into the enclosing vector (see ‘Examples’). transpose is a special map application that concatenates its inputs to compute a transposed list.

Usage

map(.f, ...)

flatmap(.f, ..., .default)

flatmap_chr(.f, ...)

vmap(.f, .x, ..., .default)

map_int(.f, ...)

map_lgl(.f, ...)

map_chr(.f, ...)

transpose(...)

Arguments

.f	an n-ary function where n is the number of further arguments given
...	lists of arguments to map over in parallel
.default	the default value returned by flatmap for an empty input

Value

map returns a (potentially nested) list of values resulting from applying .f to the arguments.

flatmap returns a vector with type given by .default, or .default, if the input is empty.

transpose returns a list of the element-wise concatenated input vectors; that is, a “transposed list” of those elements.

Examples

flatmap_chr(identity, NULL)
# character(0)

flatmap_chr(identity, c('a', 'b'))
# [1] "a" "b"

flatmap_chr(identity, list(c('a', 'b'), 'c'))
# [1] "a" "b" "c"

transpose(1 : 2, 3 : 4)
# [[1]]
# [1] 1 3
#
# [[2]]
# [1] 2 4

box documentation built on May 2, 2023, 9:14 a.m.