BUG: lib: Simplify (and fix) pad's handling of the pad_width

Simplify the expansion of the pad_width argument by using `broadcast_to()`.
This fixes the problem reported in gh-7808, where, for example,
`pad_width=((1, 2),)` resulted in an error.

Closes gh-7808.

1 files changed, 18 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_arraypad.py b/numpy/lib/tests/test_arraypad.py
index 9ad05906d..d037962e6 100644
--- a/numpy/lib/tests/test_arraypad.py
+++ b/numpy/lib/tests/test_arraypad.py
@@ -914,6 +914,24 @@ class TestEdge(TestCase):
             )
         assert_array_equal(a, b)
 
+    def test_check_width_shape_1_2(self):
+        # Check a pad_width of the form ((1, 2),).
+        # Regression test for issue gh-7808.
+        a = np.array([1, 2, 3])
+        padded = pad(a, ((1, 2),), 'edge')
+        expected = np.array([1, 1, 2, 3, 3, 3])
+        assert_array_equal(padded, expected)
+
+        a = np.array([[1, 2, 3], [4, 5, 6]])
+        padded = pad(a, ((1, 2),), 'edge')
+        expected = pad(a, ((1, 2), (1, 2)), 'edge')
+        assert_array_equal(padded, expected)
+
+        a = np.arange(24).reshape(2, 3, 4)
+        padded = pad(a, ((1, 2),), 'edge')
+        expected = pad(a, ((1, 2), (1, 2), (1, 2)), 'edge')
+        assert_array_equal(padded, expected)
+
 
 class TestZeroPadWidth(TestCase):
     def test_zero_pad_width(self):