How to find unique values in a matrix without looping over rows

Question

France Poirier 2021-1-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/728838-how-to-find-unique-values-in-a-matrix-without-looping-over-rows

回答： Stephen23 2021-1-27

Hi,

I have an m by n matrix A that has repeat non-zero values in every row. The number of non-zero elements varies across rows. I would like to keep only unique values, but can't seem to figure out how to do that without looping. Matrix size is big, so I tried looping and it's not an option...

I tried using unique function, but can't get it to do what I need. I would appreciate any advice.

Thank you,

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Answer 1

Cris LaPierre 2021-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/728838-how-to-find-unique-values-in-a-matrix-without-looping-over-rows#answer_607783

在 MATLAB Online 中打开

out = unique(A(:))

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Answer 2

Stephen23 2021-1-27

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https://ww2.mathworks.cn/matlabcentral/answers/728838-how-to-find-unique-values-in-a-matrix-without-looping-over-rows#answer_607818

在 MATLAB Online 中打开

M = randi([0,9],3,13)
M = 3×13
     3     6     6     9     8     5     7     8     6     7     1     4     5
     1     4     5     3     6     5     4     9     4     3     7     5     6
     2     1     6     0     7     5     8     4     3     8     4     0     0
W = sort(M,2);
W(diff(W,1,2)==0) = 0;
W = sort(W,2) % optional
W = 3×13
     0     0     0     0     0     1     3     4     5     6     7     8     9
     0     0     0     0     0     0     1     3     4     5     6     7     9
     0     0     0     0     0     1     2     3     4     5     6     7     8