Parallel pool: Conversion to double from cell is not possible

Question

Light.16 2017-2-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/323564-parallel-pool-conversion-to-double-from-cell-is-not-possible

回答： Edric Ellis 2017-2-7

Hello guys!

i'm trying to solve this problem. I started this loop (where B is a table).

    parfor i=1:116676;
       if G(i)== 1;
      S(i,:)= table2cell(B(i,:));
       end
    end

My problem is that is i run the loop without "parfor" it works... but if i use "parfor" the cicle doesn't works and Matlab told me:

Conversion to double from cell is not possible.

What can i do for solve this problem?

thank you :D

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Answer 1

Edric Ellis 2017-2-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/323564-parallel-pool-conversion-to-double-from-cell-is-not-possible#answer_253687

The problem here is that you haven't pre-allocated S, and unfortunately this doesn't quite work out correctly in parfor. The simple fix is to pre-allocate S to be a cell array of the correct size.

B = table(rand(10,1), rand(10,1));
G = rand(height(B),1) > 0.5;
S = cell(height(B), width(B));
parfor i=1:height(B)
    if G(i)== 1
        S(i,:)= table2cell(B(i,:));
    end
end