Uses the parallelization mode and the other options specified in parallelStart().

Libraries and source file can be initialized on slaves with parallelLibrary() and parallelSource().

Large objects can be separately exported via parallelExport(), they can be simply used under their exported name in slave body code.

Regarding error handling, see the argument impute.error.

  more.args = list(),
  simplify = FALSE,
  use.names = FALSE,
  impute.error = NULL,
  level = NA_character_, = NA



Function to map over ....


Arguments to vectorize over (list or vector).


A list of other arguments passed to fun. Default is empty list.


Should the result be simplified? See simplify2array. If TRUE, simplify2array(higher = TRUE) will be called on the result object. Default is FALSE.


Should result be named? Use names if the first ... argument has names, or if it is a character vector, use that character vector as the names.


(NULL | function(x))
This argument can be used for improved error handling. NULL means that, if an exception is generated on one of the slaves, it is also thrown on the master. Usually all slave jobs will have to terminate until this exception on the master can be thrown. If you pass a constant value or a function, all jobs are guaranteed to return a result object, without generating an exception on the master for slave errors. In case of an error, this is a simpleError() object containing the error message. If you passed a constant object, the error-objects will be substituted with this object. If you passed a function, it will be used to operate on these error-objects (it will ONLY be applied to the error results). For example, using identity would keep and return the simpleError-object, or function(x) 99 would impute a constant value (which could be achieved more easily by simply passing 99). Default is NULL.


If a (non-missing) level is specified in parallelStart(), this call is only parallelized if the level specified here matches. Useful if this function is used in a package. Default is NA.

Verbose output on console? Can be used to override setting from options / parallelStart(). Default is NA which means no overriding.




parallelStart() parallelMap(identity, 1:2)
#> [[1]] #> [1] 1 #> #> [[2]] #> [1] 2 #>