[eigen] sparse.h : use scipy's API to sort indices for Eigen<3.4.90

Author: ManifoldFR

include/nanobind/eigen/sparse.h

@@ -62,6 +62,12 @@ template <typename T> struct type_caster<T, enable_if_t<is_eigen_sparse_matrix_v
             return false;
         }
 
+#if !EIGEN_VERSION_AT_LEAST(3, 4, 90)
+        bool indices_sorted = cast<bool>(obj.attr("has_sorted_indices"));
+        if (!indices_sorted)
+            obj.attr("sort_indices")();
+#endif
+
         if (object data_o = obj.attr("data"); !data_caster.from_python(data_o, flags, cleanup))
             return false;
         ScalarNDArray& values = data_caster.value;

tests/test_eigen.py

@@ -264,9 +264,6 @@ def test08_sparse():
     assert type(t.sparse_copy_r(t.sparse_c())) is scipy.sparse.csr_matrix
     assert type(t.sparse_copy_c(t.sparse_r())) is scipy.sparse.csc_matrix
 
-    # construct scipy matrix with unsorted indices
-    assert type(t.sparse_copy_c(create_spmat_unsorted())) is scipy.sparse.csc_matrix
-
 
     def assert_sparse_equal_ref(sparse_mat):
         ref = np.array(
@@ -286,7 +283,11 @@ def assert_sparse_equal_ref(sparse_mat):
     assert_sparse_equal_ref(t.sparse_copy_c(t.sparse_c()))
     assert_sparse_equal_ref(t.sparse_copy_r(t.sparse_c()))
     assert_sparse_equal_ref(t.sparse_copy_c(t.sparse_r()))
-    assert_sparse_equal_ref(t.sparse_copy_c(create_spmat_unsorted()))
+
+    # construct scipy matrix with unsorted indices
+    assert type(t.sparse_copy_c(create_spmat_unsorted())) is scipy.sparse.csc_matrix
+    mat_unsort = create_spmat_unsorted()
+    assert_array_equal(t.sparse_copy_c(mat_unsort).toarray(), create_spmat_unsorted().toarray())
 
 
 @needs_numpy_and_eigen