Apply a function to each element of a vector, and its index via futures

These functions work the same as purrr::imap() functions, but allow you to map in parallel.

Usage

future_imap(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_chr(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_dbl(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_int(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_lgl(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_vec(
  .x,
  .f,
  ...,
  .ptype = NULL,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_dfr(
  .x,
  .f,
  ...,
  .id = NULL,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_imap_dfc(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

future_iwalk(
  .x,
  .f,
  ...,
  .options = furrr_options(),
  .env_globals = parent.frame(),
  .progress = FALSE
)

Arguments

.x

A list or atomic vector.

.f

A function, specified in one of the following ways:

• A named function, e.g. paste.

• An anonymous function, e.g. \(x, idx) x + idx or function(x, idx) x + idx.

• A formula, e.g. ~ .x + .y. Use .x to refer to the current element and .y to refer to the current index. No longer recommended.

...

Additional arguments passed on to the mapped function.

We now generally recommend against using ... to pass additional (constant) arguments to .f. Instead use a shorthand anonymous function:

# Instead of
x |> future_map(f, 1, 2, collapse = ",")
# do:
x |> future_map(\(x) f(x, 1, 2, collapse = ","))

This makes it easier to understand which arguments belong to which function and will tend to yield better error messages.

.options

The future specific options to use with the workers. This must be the result from a call to furrr_options().

.env_globals

The environment to look for globals required by .x and .... Globals required by .f are looked up in the function environment of .f.

.progress

A single logical. Should a progress bar be displayed? Only works with multisession, multicore, and multiprocess futures. Note that if a multicore/multisession future falls back to sequential, then a progress bar will not be displayed.

Warning: The .progress argument will be deprecated and removed in a future version of furrr in favor of using the more robust progressr package.

.ptype

If NULL, the default, the output type is the common type of the elements of the result. Otherwise, supply a "prototype" giving the desired type of output.

.id

Either a string or NULL. If a string, the output will contain a variable with that name, storing either the name (if .x is named) or the index (if .x is unnamed) of the input. If NULL, the default, no variable will be created.

Only applies to _dfr variant.

Value

A vector the same length as .x.

Examples

plan(multisession, workers = 2)

future_imap_chr(sample(10), ~ paste0(.y, ": ", .x))
#>  [1] "1: 7"  "2: 5"  "3: 6"  "4: 10" "5: 4"  "6: 1"  "7: 9"  "8: 8"  "9: 3" 
#> [10] "10: 2"