remove non-unique columns even if the sign has changed

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LC
LC 2025-2-4
评论： Les Beckham 2025-2-4
I have a 76x16 matrix. Some of the data is repeated and I want to remove repeated columns, which I have tried to do below. However, the numbers are the same but the sign has changed, e.g. columns 8 and 14 are the same data but the signs are reversed (where 8 is +ve, 14 is -ve etc), which my code doesn't acocunt for. The +ve/-ve matters so I cant just abs() the dataset.
I want to keep the first occurence of the repeated columns, where I should be left with 6 columns of data. Can anybody help?
mlag= unique(newca1.','rows','stable').'
mlag(:,max(mlag) == 0) = [];

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采纳的回答

Les Beckham
Les Beckham 2025-2-4
Ran in:
Perhaps this?
load newca.mat
[~, icol, ~] = unique(abs(newca1).', 'rows', 'stable')
icol = 7×1
1 2 3 4 7 8 12
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mlag = newca1(:,icol)
mlag = 76×7
0 0 0 0 0 0.1250 0 0 0 0 0 0 0.1111 0 0 0 0 0 0 0.1000 0 0 0.0909 0.0909 0.0909 0.0909 0.0909 0 0 0.1667 0.1667 0.1667 0.0833 0.0833 0 0 0.1538 0.1538 0.2308 0.0769 0.0769 0 0 0.3571 0.0714 0.3571 -0.2143 0.1429 0.2857 0 0.1333 0.0667 0.3333 0 0.3333 0.2667 0 0.1333 0.0667 0.3333 -0.0667 0.3333 0.2667 0 0.1333 0.0667 0.2667 -0.0667 0.3333 0.2667
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更多回答（1 个）

Steven Lord
Steven Lord 2025-2-4
编辑：Steven Lord 2025-2-4
Make a copy of newca1, let's call it M. Multiply each column of M whose first element is negative by -1. This way if you think of your columns as vectors, they're all pointing "right" (towards +Inf along the x axis, if this were a 2-dimensional problem.) Call unique on M and ask not only for the unique rows but also the indices of the unique rows. Use the indices to extract the corresponding columns of newca1.

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