how to slice variables to use parfor

3 次查看(过去 30 天)
Hi,
I cannot convert this for loop into a parfor loop: I tried to have a look to the help but I cannot understand how to slice this variable to use the parfor istead of the for loop.
tot_rows = randi([10000,20000],1);
tot_cols = randi([10,500],1);
data = zeros(tot_rows, tot_cols);
for k=1:tot_cols
idx = randi([1 tot_rows], randi([1 tot_rows]), 1); %now is generated randomly, then in real version idx is found with a criteria...
tmp = rand(length(idx),1);%now is generated randomly, then in real version tmp is taken from txt file...
data(idx,k) = tmp;
end
If I try to use the parfor loop I get the following error, I suppose because "data" array cannot be recalled in this way but I cannot understand how to slice it:
tot_rows = randi([10000,20000],1);
tot_cols = randi([10,500],1);
data = zeros(tot_rows, tot_cols);
parfor k=1:tot_cols
idx = randi([1 tot_rows], randi([1 tot_rows]), 1); %now is generated randomly, then in real version idx is found with a criteria...
tmp = rand(length(idx),1);%now is generated randomly, then in real version tmp is taken from txt file...
data(idx,k) = tmp;
end
Error using test_for (line 6)
Error: Unable to classify the variable 'data' in the body of the parfor-loop. For more information, see Parallel for Loops in MATLAB, "Solve Variable Classification Issues in parfor-Loops".
Thanks everyone for the help! :)

采纳的回答

Matt J
Matt J 2021-3-20
编辑:Matt J 2021-3-20
One way,
[I,J,S]=deal(cell(tot_cols,1));
parfor k=1:tot_cols
idx = randi([1 tot_rows], randi([1 tot_rows]), 1); %now is generated randomly, then in real version idx is found with a criteria...
tmp = rand(length(idx),1);%now is generated randomly, then in real version tmp is taken from txt file...
[I{k} ,J{k},S{k}]=deal(idx,idx,tmp);
J{k}(:)=k;
end
data = accumarray(cell2mat([I,J]), cell2mat(S),[tot_rows, tot_cols]);

更多回答(0 个)

类别

Help CenterFile Exchange 中查找有关 Loops and Conditional Statements 的更多信息

产品


版本

R2020a

Community Treasure Hunt

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

Start Hunting!

Translated by