从数组中删除非唯一行 [英] Deleting non-unique rows from an array

问题描述

我有一个数组a，如下所示:

I have an array a as follows:

a = [ 1 2; 3 4; 1 2 ];

我想删除在a中出现多次的所有行并获取c:

I want to delete all rows appearing more than once in a and get c:

c = [ 3 4 ];

请注意，这与保留唯一行不同，因为我根本不希望出现重复的行.我该怎么做?

Please note that this is not the same operation as keeping unique rows, since I don't want rows that had duplicates to appear at all. How can I accomplish this?

推荐答案

accumarray 一起使用，以计算出现次数，可以用来选择仅出现一次的行.

The third output of unique gives you the index of the unique row in the original array. You can use this with accumarray to count the number of occurrences, which can be used to select rows that occur only once.

例如:

A = [1 2; 3 4; 1 2];

[uniquerow, ~, rowidx] = unique(A, 'rows'); 
noccurrences = accumarray(rowidx, 1);

C = uniquerow(noccurrences==1, :);

哪个返回:

>> C

C =

     3     4

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