Kmedians ccore implementation, calculate_median simple bug

Ouverte

#708 ouverte le 9/7/2025 0 commentaires 0 réactions 0 personnes assignées Voir sur GitHub

Langage dominant: Python
Étoiles: 1.2k
Forks: 262
Métriques de merge des PR: Aucune PR mergée en 30 j

Description

Should a new version of pyclustering be released in the future. I would like to report a bug on the component-wise median calculation of the ccore implementation of KMedians in kmedians.cpp, which is inconsistent with the Python implementation. The issue is that the ccore flag is by default set to True, so the ccore implementation is used by default.

In lines 150-154, the sort is a lexicographical sort, instead of sorting on a dimension basis for component-wise median calculation.
https://github.com/annoviko/pyclustering/blob/906532e4a5422479cc6813e852f9c3cb48ea7a64/ccore/src/cluster/kmedians.cpp#L149-L154

Simple proposed fix

for (size_t index_dimension = 0; index_dimension < dimension; index_dimension++) {

          std::sort(current_cluster.begin(), current_cluster.end(), 

                [this, &index_dimension](std::size_t index_object1, std::size_t index_object2) 

            {

                 return (*m_ptr_data)[index_object1][index_dimension] > (*m_ptr_data)[index_object2][index_dimension];

            });

...

Minimum reproducible code

_median1_ is the ccore implementation output, and _median2_ is the python implementation output

Guide de contribution

Aucun guide de contribution indexé pour ce dépôt

Évaluation

Cette issue n'a pas encore été évaluée.