Reascertain that linspace respects ndarray subclasses in start, stop.

2 files changed, 22 insertions, 4 deletions

diff --git a/numpy/core/function_base.py b/numpy/core/function_base.py
index c82c9bb6b..21ca1af01 100644
--- a/numpy/core/function_base.py
+++ b/numpy/core/function_base.py
@@ -96,18 +96,23 @@ def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
 
     y = _nx.arange(0, num, dtype=dt)
 
+    delta = stop - start
     if num > 1:
-        delta = stop - start
         step = delta / div
         if step == 0:
             # Special handling for denormal numbers, gh-5437
             y /= div
-            y *= delta
+            y = y * delta
         else:
-            y *= step
+            # One might be tempted to use faster, in-place multiplication here,
+            # but this prevents step from overriding what class is produced,
+            # and thus prevents, e.g., use of Quantities; see gh-7142.
+            y = y * step
     else:
         # 0 and 1 item long sequences have an undefined step
         step = NaN
+        # Multiply with delta to allow possible override of output class.
+        y = y * delta
 
     y += start
 
diff --git a/numpy/core/tests/test_function_base.py b/numpy/core/tests/test_function_base.py
index 2df7ba3ea..6b5430611 100644
--- a/numpy/core/tests/test_function_base.py
+++ b/numpy/core/tests/test_function_base.py
@@ -1,7 +1,7 @@
 from __future__ import division, absolute_import, print_function
 
 from numpy import (logspace, linspace, dtype, array, finfo, typecodes, arange,
-                   isnan)
+                   isnan, ndarray)
 from numpy.testing import (
     TestCase, run_module_suite, assert_, assert_equal, assert_raises,
     assert_array_equal
@@ -115,6 +115,19 @@ class TestLinspace(TestCase):
         b = PhysicalQuantity(1.0)
         assert_equal(linspace(a, b), linspace(0.0, 1.0))
 
+    def test_subclass(self):
+        class PhysicalQuantity2(ndarray):
+            __array_priority__ = 10
+
+        a = array(0).view(PhysicalQuantity2)
+        b = array(1).view(PhysicalQuantity2)
+        ls = linspace(a, b)
+        assert type(ls) is PhysicalQuantity2
+        assert_equal(ls, linspace(0.0, 1.0))
+        ls = linspace(a, b, 1)
+        assert type(ls) is PhysicalQuantity2
+        assert_equal(ls, linspace(0.0, 1.0, 1))
+
     def test_denormal_numbers(self):
         # Regression test for gh-5437. Will probably fail when compiled
         # with ICC, which flushes denormals to zero