[GitHub] [arrow] mrkn commented on a change in pull request #7477: ARROW-4221: [C++][Python] Add canonical flag in COO sparse index

[GitBox <gi...@apache.org>]

mrkn commented on a change in pull request #7477:
URL: https://github.com/apache/arrow/pull/7477#discussion_r452605554



##########
File path: python/pyarrow/tensor.pxi
##########
@@ -270,8 +279,10 @@ shape: {0.shape}""".format(self)
                                               &out_data, &out_coords))
         data = PyObject_to_object(out_data)
         coords = PyObject_to_object(out_coords)
-        result = coo_matrix((data[:, 0], (coords[:, 0], coords[:, 1])),
-                            shape=self.shape)
+        row, col = coords[:, 0], coords[:, 1]
+        result = coo_matrix((data[:, 0], (row, col)), shape=self.shape)
+        if self.has_canonical_format:
+            result.sum_duplicates()

Review comment:
       @rok Yes, if `is_canonical` is true, the indices matrix is sorted in row-major order and doesn't have duplicates.
   In other words, this flag has the same meaning as `has_canonical_format` of `scipy.sparse.coo_matrix` but the order is row-major, instead of column-major.




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