makeChunks: Create Chunks of Index Vectors

In future.apply: Apply Function to Elements in Parallel using Futures

Create Chunks of Index Vectors

Description

This is an internal function.

Usage

makeChunks(
  nbrOfElements,
  nbrOfWorkers,
  future.scheduling = 1,
  future.chunk.size = NULL
)

Arguments

nbrOfElements	(integer) Total number of elements to iterate over.
nbrOfWorkers	(integer) Number of workers available.
future.scheduling	(numeric) A strictly positive scalar. Only used if argument future.chunk.size is NULL.
future.chunk.size	(numeric) The maximum number of elements per chunk, or NULL. If NULL, then the chunk sizes are given by the future.scheduling argument.

Value

A list of chunks, where each chunk is an integer vector of unique indices [1, nbrOfElements]. The union of all chunks holds nbrOfElements elements and equals 1:nbrOfElements. If nbrOfElements == 0, then an empty list is returned.

Control processing order of elements

Attribute ordering of future.chunk.size or future.scheduling can be used to control the ordering the elements are iterated over, which only affects the processing order not the order values are returned. This attribute can take the following values:

• index vector - an numeric vector of length nbrOfElements specifying how elements are remapped

• function - an function taking one argument which is called as ordering(nbrOfElements) and which must return an index vector of length nbrOfElements, e.g. function(n) rev(seq_len(n)) for reverse ordering.

• "random" - this will randomize the ordering via random index vector sample.int(nbrOfElements).

future.apply documentation built on Oct. 28, 2024, 1:06 a.m.