as_mapper {purrr} | R Documentation |
as_mapper
is the powerhouse behind the varied function
specifications that most purrr functions allow. It is an S3
generic. The default method forwards its arguments to
rlang::as_function()
.
as_mapper(.f, ...) ## S3 method for class 'character' as_mapper(.f, ..., .null, .default = NULL) ## S3 method for class 'numeric' as_mapper(.f, ..., .null, .default = NULL) ## S3 method for class 'list' as_mapper(.f, ..., .null, .default = NULL)
.f |
A function, formula, or atomic vector. If a function, it is used as is. If a formula, e.g.
This syntax allows you to create very compact anonymous functions. If character vector, numeric vector, or list, it
is converted to an extractor function. Character vectors index by name
and numeric vectors index by position; use a list to index by position
and name at different levels. Within a list, wrap strings in |
... |
Additional arguments passed on to methods. |
.default, .null |
Optional additional argument for extractor functions
(i.e. when |
as_mapper(~ . + 1) as_mapper(1) as_mapper(c("a", "b", "c")) # Equivalent to function(x) x[["a"]][["b"]][["c"]] as_mapper(list(1, "a", 2)) # Equivalent to function(x) x[[1]][["a"]][[2]] as_mapper(list(1, attr_getter("a"))) # Equivalent to function(x) attr(x[[1]], "a") as_mapper(c("a", "b", "c"), .null = NA)