Merge pull request numpy#11979 from hmaarrfk/block_single_array_copy_test

mattip · web-flow · commit db5f9d3a61d6 · 2018-10-09T13:31:20.000+03:00
MAINT: Ensure that a copy of the array is returned when calling `block`.
diff --git a/numpy/core/shape_base.py b/numpy/core/shape_base.py
@@ -617,4 +617,11 @@ def block(arrays):
                 _block_format_index(bottom_index)
             )
         )
-    return _block(arrays, list_ndim, max(arr_ndim, list_ndim))
+    result = _block(arrays, list_ndim, max(arr_ndim, list_ndim))
+    if list_ndim == 0:
+        # Catch an edge case where _block returns a view because
+        # `arrays` is a single numpy array and not a list of numpy arrays.
+        # This might copy scalars or lists twice, but this isn't a likely
+        # usecase for those interested in performance
+        result = result.copy()
+    return result
diff --git a/numpy/core/tests/test_shape_base.py b/numpy/core/tests/test_shape_base.py
@@ -191,6 +191,12 @@ def test_2D_array2(self):
 
 
 class TestConcatenate(object):
+    def test_returns_copy(self):
+        a = np.eye(3)
+        b = np.concatenate([a])
+        b[0, 0] = 2
+        assert b[0, 0] != a[0, 0]
+
     def test_exceptions(self):
         # test axis must be in bounds
         for ndim in [1, 2, 3]:
@@ -367,6 +373,12 @@ def test_stack():
 
 
 class TestBlock(object):
+    def test_returns_copy(self):
+        a = np.eye(3)
+        b = np.block(a)
+        b[0, 0] = 2
+        assert b[0, 0] != a[0, 0]
+
     def test_block_simple_row_wise(self):
         a_2d = np.ones((2, 2))
         b_2d = 2 * a_2d

Original file line number	Diff line number	Diff line change
`@@ -617,4 +617,11 @@ def block(arrays):`
`617`	`617`	`_block_format_index(bottom_index)`
`618`	`618`	`)`
`619`	`619`	`)`
`620`		`- return _block(arrays, list_ndim, max(arr_ndim, list_ndim))`
	`620`	`+ result = _block(arrays, list_ndim, max(arr_ndim, list_ndim))`
	`621`	`+ if list_ndim == 0:`
	`622`	`+ # Catch an edge case where _block returns a view because`
	`623`	+ # `arrays` is a single numpy array and not a list of numpy arrays.
	`624`	`+ # This might copy scalars or lists twice, but this isn't a likely`
	`625`	`+ # usecase for those interested in performance`
	`626`	`+ result = result.copy()`
	`627`	`+ return result`