Return values in a parfor loop

20 views (last 30 days)
Wave on 14 May 2020
Commented: Wave on 15 May 2020
at the moment my source code looks like this
ParForQueue = parallel.pool.DataQueue;
parfor m = 1:Anzahl
send(ParForQueue, Satz)
function [] = AddStruct(Satz)
global TabellenRueckgabe
My question is: how is it possible to avoid the global variable. I want to use the function like this instead of using global
function [TabellenRueckgabe] = AddStruct(Satz, TabellenRueckgabe)
TabellenRueckgabe(x) = Satz;

Accepted Answer

Edric Ellis
Edric Ellis on 15 May 2020
Fundamentally, you need to "bind" a value in to the function that gets invoked by afterEach. The simplest way to do this is to use a nested function. Here's an example: in this case, the result vector has elements assigned when data queue messages are received:
function result = doStuff
q = parallel.pool.DataQueue;
% Pre-allocate the return value for the function
result = NaN(1, 20);
% This nested function modifies entries of 'result'
function nAccumulate(msg)
idx = msg(1);
val = msg(2);
result(idx) = val;
% Hook up our DataQueue to the nested function. The nested function
% handle can see and modify 'result'.
afterEach(q, @nAccumulate);
% Run the parfor loop, sending back updates.
parfor ii = 1:10
idx = randi(20);
val = rand();
% This will cause the idx'th element of 'result' to get the value
% 'val'.
send(q, [idx, val]);
  1 Comment
Wave on 15 May 2020
Good idea. Thank you!

Sign in to comment.

More Answers (0)

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!