map_along_dim | R Documentation |
map_along_dim(X, dim, func)
is a simple wrapper around split_along_dim(X, dim) %>% map(func)
. It is conceptually and functionally equivalent to
base::apply()
, with the following key differences:
it is guaranteed to return a list (base::apply()
attempts to simplify the
output to an array, sometimes unsuccessfully, making the output unstable)
it accepts the compact lambda notation ~.x
just like in purrr::map
(and modify_along_dim()
)
map_along_dim(X, .dim, .f, ...)
map_along_rows(X, .f, ...)
map_along_cols(X, .f, ...)
X |
an R array |
.dim |
which dimension to map along. Passed on to
|
.f |
A function, string of a function name, or |
... |
passed on to |
An R list
X <- matrix2(letters[1:15], ncol = 3)
apply(X, 1, function(x) paste(x, collapse = "")) # simplifies to a vector
map_along_dim(X, 1, ~paste(.x, collapse = "")) # returns a list
identical(
map_along_rows(X, identity),
map_along_dim(X, 1, identity)) # TRUE
identical(
map_along_cols(X, identity),
map_along_dim(X, -1, identity)) # TRUE
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