如何在matlab中找到具有重复的矩阵的每一行的索引？ [英] How can I find indices of each row of a matrix which has a duplicate in matlab?

问题描述

我想找到具有重复的矩阵的所有行的索引。例如

I want to find the indices all the rows of a matrix which have duplicates. For example

A = [1 2 3 4
     1 2 3 4
     2 3 4 5
     1 2 3 4
     6 5 4 3]

要返回的向量将是 [1,2,4]

很多类似的问题建议使用唯一的函数，我尝试过但最接近我想要的是：

A lot of similar questions suggest using the unique function, which I've tried but the closest I can get to what I want is:

[C, ia, ic] = unique(A, 'rows')

ia = [1 3 5]
m = 5;
setdiff(1:m,ia) = [2,4]

但是使用 unique 我只能提取一行的第二，第三，第四...等实例，我还需要获得第一个。有什么办法可以做到吗？

But using unique I can only extract the 2nd,3rd,4th...etc instance of a row, and I need to also obtain the first. Is there any way I can do this?

NB：它必须是一个不涉及循环遍历行的方法，因为我在处理大型稀疏矩阵。

NB: It must be a method which doesn't involve looping through the rows, as I'm dealing with large sparse matrices.

推荐答案

如何：

[~, ia, ic] = unique(A, 'rows')

setdiff(1:size(A,1), ia( sum(bsxfun(@eq,ic,(1:max(ic))))<=1 ))

这篇关于如何在matlab中找到具有重复的矩阵的每一行的索引？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！