Skip to contents

Apply Functions in the spirit of 'purrr'

Source: R/purrr_map.R
compat-map.Rd

map-like functions, similar to the ones implemented in purrr:

  • map() returns the results of .f applied to .x as list. If .f is not a function, map will call [[ on all elements of .x using the value of .f as index.

  • imap() applies .f to each value of .x (passed as first argument) and its name (passed as second argument). If .x does not have names, a sequence along .x is passed as second argument instead.

  • pmap() expects .x to be a list of vectors of equal length, and then applies .f to the first element of each vector of .x, then the second element of .x, and so on.

  • map_if() applies .f to each element of .x where the predicate .p evaluates to TRUE.

  • map_at() applies .f to each element of .x referenced by .at. All other elements remain unchanged.

  • keep() keeps those elements of .x where predicate .p evaluates to TRUE.

  • discard() discards those elements of .x where predicate .p evaluates to TRUE.

  • compact() discards elements of .x that are NULL.

  • every() is TRUE if predicate .p evaluates to TRUE for each .x.

  • some() is TRUE if predicate .p evaluates to TRUE for at least one .x.

  • detect() returns the first element where predicate .p evaluates to TRUE.

  • walk(), iwalk() and pwalk() are the counterparts to map(), imap() and pmap(), but just visit (or change by reference) the elements of .x. They return input .x invisibly.

Additionally, the functions map(), imap() and pmap() have type-safe variants with the following suffixes:

  • *_lgl() returns a logical(length(.x)).

  • *_int() returns a integer(length(.x)).

  • *_dbl() returns a double(length(.x)).

  • *_chr() returns a character(length(.x)).

  • *_br() returns an object where the results of .f are put together with base::rbind().

  • *_bc() returns an object where the results of .f are put together with base::cbind().

  • *_dtr() returns a data.table::data.table() where the results of .f are put together in an base::rbind() fashion.

  • *_dtc() returns a data.table::data.table() where the results of .f are put together in an base::cbind() fashion.

Usage

map(.x, .f, ...)

map_lgl(.x, .f, ...)

map_int(.x, .f, ...)

map_dbl(.x, .f, ...)

map_chr(.x, .f, ...)

map_br(.x, .f, ...)

map_bc(.x, .f, ...)

map_dtr(.x, .f, ..., .fill = FALSE, .idcol = NULL)

map_dtc(.x, .f, ...)

pmap(.x, .f, ...)

pmap_lgl(.x, .f, ...)

pmap_int(.x, .f, ...)

pmap_dbl(.x, .f, ...)

pmap_chr(.x, .f, ...)

pmap_dtr(.x, .f, ..., .fill = FALSE, .idcol = NULL)

pmap_dtc(.x, .f, ...)

imap(.x, .f, ...)

imap_lgl(.x, .f, ...)

imap_int(.x, .f, ...)

imap_dbl(.x, .f, ...)

imap_chr(.x, .f, ...)

imap_dtr(.x, .f, ..., .fill = FALSE, .idcol = NULL)

imap_dtc(.x, .f, ...)

keep(.x, .f, ...)

discard(.x, .p, ...)

compact(.x)

map_if(.x, .p, .f, ...)

# Default S3 method
map_if(.x, .p, .f, ...)

map_at(.x, .at, .f, ...)

every(.x, .p, ...)

some(.x, .p, ...)

detect(.x, .p, ...)

walk(.x, .f, ...)

iwalk(.x, .f, ...)

pwalk(.x, .f, ...)

Arguments

.x

(list() | atomic vector()).

.f

(function() | character() | integer())
Function to apply, or element to extract by name (if .f is character()) or position (if .f is integer()).

...

(any)
Additional arguments passed down to .f or .p.

.fill

(logical(1))
Passed down to data.table::rbindlist().

.idcol

(logical(1))
Passed down to data.table::rbindlist().

.p

(function() | logical())
Predicate function.

.at

(character() | integer() | logical())
Index vector.