Please help to vectorize this code.

tic;
load 'CCA_result.mat';
CleanData1= CleanData1';
rows = size(CleanData1);
Result_cpei = zeros(1,rows(1));
for N = 1:1:rows
tmp=CPEI(CleanData1(N,:),0);
Result_cpei = [Result_cpei tmp];
save ('CPEI','Result_cpei');
end
The output is not a matter since I got the right output. The issue is can this code to be vectorized?

4 个评论

  • looks wrong: &nbsp rows = size(CleanData1). &nbsp Is rows supposed to be scalar?
  • what's &nbsp CPEI ?
Thanks for your comment and answer. Yup 'rows' supposed to be scalar and I got nothing error for this.
CPEI is a function in matlab for Qeeg feature extraction. The long term is Composite Permutation Entropy Index (CPEI).
@M O: Yes, you do not get an error for for N=1:1:[a,b], but most likely this will not do what you expect. Please specify, if you want:
rows = size(CleanData1, 1)
% or
rows = size(CleanData1, 2)
% or
rows = numel(CleanData1, 1)
The created file "CPEI.mat" is overwritten in each iteration. This is not useful. Please write a clean code, which does exactly, what you want, before starting to optimize the speed by a vectorization.
Ohh..thank you..so because of that my code getting slow..?
Really thanks.

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 采纳的回答

Jan
Jan 2017-2-14
编辑:Jan 2017-2-14
Start with avoiding to re-create the formerly pre-allocated output and do not overwrite the output file in each iteration:
Data = load('CCA_result.mat'); % Avoid dynamic creation of variables
CleanData1 = Data.CleanData1';
rows = size(CleanData1, 1); % Guessed, perhaps you want NUMEL or the 2nd dim
Result_cpei = zeros(1, rows); % Pre-allocation
for N = 1:rows
Result_cpei(N) = CPEI(CleanData1(N,:),0); % Write ionto pre-allocated array
end
save('CPEI.mat', 'Result_cpei');
If this can be vectorized depends on the contents of the function CPEI. If this function accepts a array as input, the code can be simplified to:
Data = load('CCA_result.mat');
CleanData1 = Data.CleanData1';
Result_cpei = CPEI(CleanData1,0);
save('CPEI.mat', 'Result_cpei');

1 个评论

Here I attached the output of the code that you gave it to me. I want this. But its already vectorized or not? Because this code is running faster than mine previously.
But if I run this code, Its only show 1 value only.
Data = load('CCA_result.mat');
CleanData1 = Data.CleanData1';
Result_cpei = CPEI(CleanData1,0);
save('CPEI.mat', 'Result_cpei');
Anyway thanks for the code, and need some more clarification on this.
Thank you.

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M O
2017-2-14

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M O
2017-2-15

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