How to slice a 4-level cell array to perform a parlour

Question

rob 2018-8-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/415572-how-to-slice-a-4-level-cell-array-to-perform-a-parlour

评论： rob 2018-8-21

Hello Everyone, I was trying to use parfor to speed up my calculations, but without success. I'm using a cell array composed of 4 levels, which is useful for organising my data. However, it seems that if I want to use a cell array in a parfor I should index it "always in the same way" (googled it). To be honest, I can't understand why, in my specific case, the variable I'm using is not sliced, but surely you can do it better than me. I'm attaching some example code to explain my case. I'm sure you guys can help me fixing it. Thanks, Rob

%example
CLASS    = 1 : 3;
CASE     = 1 : 17;
FYcase   = 1 : 9;
FCcase   = 1 : 9;
%
for class = CLASS
  parfor caso = CASE
      for fyCASE = FYcase
          for fcCASE = FCcase
                ALLcurves{class}{caso}{fyCASE}{fcCASE} = 1; % do something
            end
        end
    end
end

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Answer 1

OCDER 2018-8-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/415572-how-to-slice-a-4-level-cell-array-to-perform-a-parlour#answer_333474

在 MATLAB Online 中打开

AllCurves = cell(1, 3);
for class = 1 : 3 
    C = AllCurves{class};
    parfor caso = 1 : 17 
        A = C{caso};
        for fyCASE = 1 : 9 
            for fcCASE = 1 : 9
                A{fyCase}{fcCASE} = 1;
            end
        end
        C{caso} = A; % do something
    end
    AllCurves{class} = C;
end

https://www.mathworks.com/help/distcomp/sliced-variable.html

To use parfor, one of the requirement must be a 1st-level indexing, as in C{caso} is ok, but C{class}{caso} is not okay (2nd level indexing on the parfor counter variable, caso.