cannot assign values to a cell during a parfor loop
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I'm trying to evaluate the output of a high number of url in my domain, but I cannot deal with the "parfor" loop rules.
I get the following error:
Error: Unable to classify the variable 'checklist' in the body of the parfor-loop. For more information, see Parallel for Loops in MATLAB, "Solve Variable Classification Issues in parfor-Loops".
fold_list = cellstr(strcat('Folder_',num2str((100:125).','%#4.d')));
user_lists = cellstr(strcat('User_',num2str((1:100).','%#6.d')));
base_url = 'https://mydomain.com';
n_folds = length(fold_list);
n_users = length(user_lists);
checklist = cell(n_users+1,n_folds+1);
checklist(2:end,1) = user_lists;
checklist(1,2:end) = fold_list;
parfor j=1:n_users
for k=1:n_folds
try
checklist{j+1,k+1} = webread([base_url '/' fold_list{k} '/' user_lists{j} '.txt']);
catch
checklist{j+1,k+1} = 'N/A';
end
end
end
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Accepted Answer
Jan
on 15 Jul 2022
Edited: Jan
on 15 Jul 2022
Try this:
fold_list = cellstr(strcat('Folder_',num2str((100:125).','%#4.d')));
% By the way: Simpler:
% fold_list = sprintfc('folder_%03d', (100:125).'):
user_lists = cellstr(strcat('User_',num2str((1:100).','%#6.d')));
base_url = 'https://mydomain.com';
n_folds = length(fold_list);
n_users = length(user_lists);
checklist = cell(n_users+1,n_folds+1);
checklist(2:end,1) = user_lists;
checklist(1,2:end) = fold_list;
C = cell(n_users,n_folds)
parfor j=1:n_users
for k=1:n_folds
try
C{j,k} = webread([base_url '/' fold_list{k} '/' user_lists{j} '.txt']);
catch
C{j,k} = 'N/A';
end
end
end
cecklist(2:end, 2:end) = C;
5 Comments
Bruno Luong
on 17 Jul 2022
Edited: Bruno Luong
on 17 Jul 2022
Humm it exists on mine
>> ver
-----------------------------------------------------------------------------------------------------
MATLAB Version: 9.12.0.1975300 (R2022a) Update 3
MATLAB License Number: xxxxxx
Operating System: Microsoft Windows 11 Home Version 10.0 (Build 22000)
Java Version: Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
-----------------------------------------------------------------------------------------------------
MATLAB Version 9.12 (R2022a)
MATLAB Coder Version 5.4 (R2022a)
MATLAB Compiler Version 8.4 (R2022a)
Optimization Toolbox Version 9.3 (R2022a)
Parallel Computing Toolbox Version 7.6 (R2022a)
Signal Processing Toolbox Version 9.0 (R2022a)
>> sprintfc('%f', [1:3]) % yeah close your eyes master
ans =
1×3 cell array
{'1.000000'} {'2.000000'} {'3.000000'}
>> which sprintfc
built-in
>>
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