DOC comment on obscure syntax

jnothman · jnothman · commit a24b93209513 · 2015-09-20T22:30:26.000+10:00
diff --git a/examples/bicluster/bicluster_newsgroups.py b/examples/bicluster/bicluster_newsgroups.py
@@ -132,6 +132,8 @@ def bicluster_ncut(i):
         return sys.float_info.max
     row_complement = np.nonzero(np.logical_not(cocluster.rows_[i]))[0]
     col_complement = np.nonzero(np.logical_not(cocluster.columns_[i]))[0]
+    # Note: the following is identical to X[rows[:, np.newaxis], cols].sum() but
+    # much faster in scipy <= 0.16
     weight = X[rows][:, cols].sum()
     cut = (X[row_complement][:, cols].sum() +
            X[rows][:, col_complement].sum())
