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Evaluate an R command and return results as a monad.

Source: R/crew_eval.R
crew_eval.Rd

Not a user-side function. Do not call directly.

Usage

crew_eval(
  command,
  name,
  data = list(),
  globals = list(),
  seed = NULL,
  algorithm = NULL,
  packages = character(0),
  library = NULL,
  reset_globals = TRUE,
  reset_packages = FALSE,
  reset_options = FALSE,
  garbage_collection = FALSE
)

Arguments

command

Language object with R code to run.

name

Character of length 1, name of the task.

data

Named list of local data objects in the evaluation environment.

globals

Named list of objects to temporarily assign to the global environment for the task.

seed

Integer of length 1 with the pseudo-random number generator seed to set for the evaluation of the task. Passed to the seed argument of set.seed() if not NULL. If algorithm and seed are both NULL, then the random number generator defaults to the recommended widely spaced worker-specific L'Ecuyer streams as supported by mirai::nextstream(). See vignette("parallel", package = "parallel") for details.

algorithm

Integer of length 1 with the pseudo-random number generator algorithm to set for the evaluation of the task. Passed to the kind argument of RNGkind() if not NULL. If algorithm and seed are both NULL, then the random number generator defaults to the recommended widely spaced worker-specific L'Ecuyer streams as supported by mirai::nextstream(). See vignette("parallel", package = "parallel") for details.

packages

Character vector of packages to load for the task.

library

Library path to load the packages. See the lib.loc argument of require().

reset_globals

TRUE to reset global environment variables between tasks, FALSE to leave them alone.

reset_packages

TRUE to detach any packages loaded during a task (runs between each task), FALSE to leave packages alone. In either case, the namespaces are not detached.

reset_options

TRUE to reset global options to their original state between each task, FALSE otherwise. It is recommended to only set reset_options = TRUE if reset_packages is also TRUE because packages sometimes rely on options they set at loading time. for this and other reasons, reset_options only resets options that were nonempty at the beginning of the task. If your task sets an entirely new option not already in options(), then reset_options = TRUE does not delete the option.

garbage_collection

TRUE to run garbage collection after each task task, FALSE to skip.

Value

A monad object with results and metadata.

Details

The crew_eval() function evaluates an R expression in an encapsulated environment and returns a monad with the results, including warnings and error messages if applicable. The random number generator seed, globals, and global options are restored to their original values on exit.

See also

Other utility: crew_assert(), crew_clean(), crew_deprecate(), crew_random_name(), crew_retry(), crew_terminate_process(), crew_terminate_signal(), crew_worker()

Examples

crew_eval(quote(1 + 1), name = "task_name")
#> # A tibble: 1 × 13
#>   name  command result status error  code trace warnings seconds  seed algorithm
#>   <chr> <chr>   <list> <chr>  <chr> <int> <chr> <chr>      <dbl> <int> <chr>    
#> 1 task… 1 + 1   <dbl>  succe… NA        0 NA    NA             0    NA NA       
#> # ℹ 2 more variables: controller <chr>, worker <chr>