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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/future-map.R
\name{future_map_if}
\alias{future_map_if}
\alias{future_map_at}
\title{Apply a function to each element of a vector conditionally via futures}
\usage{
future_map_if(
.x,
.p,
.f,
...,
.else = NULL,
.options = furrr_options(),
.env_globals = parent.frame(),
.progress = FALSE
)
future_map_at(
.x,
.at,
.f,
...,
.options = furrr_options(),
.env_globals = parent.frame(),
.progress = FALSE
)
}
\arguments{
\item{.x}{A list or atomic vector.}
\item{.p}{A single predicate function, a formula describing such a
predicate function, or a logical vector of the same length as \code{.x}.
Alternatively, if the elements of \code{.x} are themselves lists of
objects, a string indicating the name of a logical element in the
inner lists. Only those elements where \code{.p} evaluates to
\code{TRUE} will be modified.}
\item{.f}{A function, formula, or vector (not necessarily atomic).
If a \strong{function}, it is used as is.
If a \strong{formula}, e.g. \code{~ .x + 2}, it is converted to a function. There
are three ways to refer to the arguments:
\itemize{
\item For a single argument function, use \code{.}
\item For a two argument function, use \code{.x} and \code{.y}
\item For more arguments, use \code{..1}, \code{..2}, \code{..3} etc
}
This syntax allows you to create very compact anonymous functions.
If \strong{character vector}, \strong{numeric vector}, or \strong{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. If a component is not
present, the value of \code{.default} will be returned.}
\item{...}{Additional arguments passed on to the mapped function.}
\item{.else}{A function applied to elements of \code{.x} for which \code{.p}
returns \code{FALSE}.}
\item{.options}{The \code{future} specific options to use with the workers. This
must be the result from a call to \code{\link[=furrr_options]{furrr_options()}}.}
\item{.env_globals}{The environment to look for globals required by \code{.x} and
\code{...}. Globals required by \code{.f} are looked up in the function environment
of \code{.f}.}
\item{.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.
\strong{Warning:} The \code{.progress} argument will be deprecated and removed
in a future version of furrr in favor of using the more robust
\href{https://CRAN.R-project.org/package=progressr}{progressr}
package.}
\item{.at}{A character vector of names, positive numeric vector of
positions to include, or a negative numeric vector of positions to
exlude. Only those elements corresponding to \code{.at} will be modified.
If the \code{tidyselect} package is installed, you can use \code{vars()} and
the \code{tidyselect} helpers to select elements.}
}
\value{
Both functions return a list the same length as \code{.x} with the
elements conditionally transformed.
}
\description{
These functions work exactly the same as \code{\link[purrr:map_if]{purrr::map_if()}} and
\code{\link[purrr:map_if]{purrr::map_at()}}, but allow you to run them in parallel.
}
\examples{
\donttest{plan(multisession, workers = 2)}
# Modify the even elements
future_map_if(1:5, ~.x \%\% 2 == 0L, ~ -1)
future_map_at(1:5, c(1, 5), ~ -1)
\dontshow{
# Close open connections for R CMD Check
if (!inherits(plan(), "sequential")) plan(sequential)
}
}
|
