Sum groups of columns

Question

Millie Johnston 2022-9-24

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https://ww2.mathworks.cn/matlabcentral/answers/1811315-sum-groups-of-columns

评论： Millie Johnston 2022-9-24

Hello,

I have a 10x4600 matrix and I would like to sum all the content in 50 column groups, i.e., sum all of the contents in cols 1-50 then 51-100 etc., greating a 1x92 matrix.

What is the best way to do this?

Any advice is much appreciated

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Answer 1

Turlough Hughes 2022-9-24

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在 MATLAB Online 中打开

Here's another option:

a = rand(10,4600);
b = mat2cell(a,height(a),repmat(50,1,width(a)/50));
result = cellfun(@(x) sum(x,'all'),b)
result = 1×92
  248.7251  241.6021  250.5905  252.4766  255.2734  248.3946  249.4391  246.7810  251.7672  249.2486  251.6410  245.3834  253.4206  259.4736  245.6898  251.8762  241.4311  255.5951  253.3935  244.1446  249.9427  254.0830  253.6857  245.3108  252.2754  247.8954  251.1564  250.9599  244.3892  250.7689

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Millie Johnston 2022-9-24

Thank you!

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Answer 2

Davide Masiello 2022-9-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1811315-sum-groups-of-columns#answer_1059870

编辑：Davide Masiello 2022-9-24

在 MATLAB Online 中打开

Example

M = rand(10,4600);
n = 50;
for idx = 1:size(M,2)/n
    S(idx) = sum(M(:,n*(idx-1)+1:n*idx),'all');
end
size(S)
ans = 1×2
     1    92
S
S = 1×92
  251.4836  239.6670  250.9846  257.7764  245.8032  240.2424  251.1242  243.9000  242.6086  251.5657  248.0851  255.3710  247.0354  250.5451  246.9072  253.7353  246.9934  245.9795  248.1267  239.6427  242.5911  244.9033  248.7932  260.2680  251.8315  242.8476  254.6372  262.0528  252.7250  259.5901