BUG: sparse: Use _ascontainer for argmin/argmax (#18121)

* BUG: sparse: Use _ascontainer for argmin/argmax

* Adding test coverage

* Remove unused import

* skip sparse formats that don't support min/max

scipy/sparse/_data.py

@@ -9,7 +9,7 @@
 import numpy as np
 
 from ._base import spmatrix, _ufuncs_with_fixed_point_at_zero
-from ._sputils import isscalarlike, validateaxis, matrix
+from ._sputils import isscalarlike, validateaxis
 
 __all__ = []
 
@@ -250,7 +250,7 @@ def _arg_min_or_max_axis(self, axis, op, compare):
         if axis == 1:
             ret = ret.reshape(-1, 1)
 
-        return matrix(ret)
+        return self._ascontainer(ret)
 
     def _arg_min_or_max(self, axis, out, op, compare):
         if out is not None:

scipy/sparse/tests/test_array_api.py

@@ -58,6 +58,23 @@ def test_mean(A):
         "Expected array, got matrix"
 
 
+@parametrize_sparrays
+def test_min_max(A):
+    # Some formats don't support min/max operations, so we skip those here.
+    if hasattr(A, 'min'):
+        assert not isinstance(A.min(axis=1), np.matrix), \
+            "Expected array, got matrix"
+    if hasattr(A, 'max'):
+        assert not isinstance(A.max(axis=1), np.matrix), \
+            "Expected array, got matrix"
+    if hasattr(A, 'argmin'):
+        assert not isinstance(A.argmin(axis=1), np.matrix), \
+            "Expected array, got matrix"
+    if hasattr(A, 'argmax'):
+        assert not isinstance(A.argmax(axis=1), np.matrix), \
+            "Expected array, got matrix"
+
+
 @parametrize_sparrays
 def test_todense(A):
     assert not isinstance(A.todense(), np.matrix), \