[MRG] Fix #13134: Ensure sorted bin edges for KBinsDiscretizer strategy kmeans #13135
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Reference Issues/PRs
Fixes #13134
What does this implement/fix? Explain your changes.
Since centers returned by 1d kmeans can be unsorted, I simply added a sort before constructing the bin edges. I also added a test which reproduces the issue when not sorting centers.
Any other comments?
Performance of sorting centers should not be an issue compared to kmeans itself. In most circumstances the list of centers is already sorted, but afaik in this situation checking if the numpy array is sorted is not better than invoking sort() directly (https://stackoverflow.com/questions/47004506/check-if-a-numpy-array-is-sorted), so I skipped the check.