Merge pull request #83 from rpsdm/fix_gmeans_split

fixed GMeans trying to split clusters with one element

clustpy/partition/gmeans.py

@@ -46,6 +46,8 @@ def _gmeans(X: np.ndarray, significance: float, n_clusters_init: int, max_n_clus
         n_clusters_old = n_clusters
         for c in range(n_clusters_old):
             ids_in_cluster = np.where(labels == c)[0]
+            if ids_in_cluster.shape[0] < 2:
+                continue
             # Split cluster into two
             labels_split, centers_split, _ = _execute_two_means(X[ids_in_cluster], [np.arange(ids_in_cluster.shape[0])], 0,
                                                              np.array([centers[c]]), n_split_trials, random_state)

clustpy/partition/xmeans.py

@@ -89,6 +89,7 @@ def _execute_two_means(X: np.ndarray, ids_in_each_cluster: list, cluster_id_to_s
         The resuling cluster centers,
         The Kmeans error of the clustering result
     """
+    assert X.shape[0] >= 2, "X must contain at least 2 elements"
     # Prepare cluster for splitting
     old_center = centers[cluster_id_to_split, :]
     reduced_centers = np.delete(centers, cluster_id_to_split, axis=0)