BUG: Fixed piecewise function for 0d input

When `x` has more than one element the condlist `[True, False]`
is being made equivalent to `[[True, False]]`, which is correct.
However, when `x` is zero dimensional the expected condlist is
`[[True], [False]]`: this commit addresses the issue. Besides,
the documentation stated that there could be undefined values
but actually these are 0 by default: using `nan` would be desirable,
but for the moment the docs were corrected. Closes #331.

1 files changed, 10 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
index cb4d6626d..ee38b3573 100644
--- a/numpy/lib/tests/test_function_base.py
+++ b/numpy/lib/tests/test_function_base.py
@@ -1487,6 +1487,7 @@ class TestPiecewise(TestCase):
         x = piecewise([0, 0], [[False, True]], [lambda x:-1])
         assert_array_equal(x, [0, -1])
 
+    def test_two_conditions(self):
         x = piecewise([1, 2], [[True, False], [False, True]], [3, 4])
         assert_array_equal(x, [3, 4])
 
@@ -1505,6 +1506,15 @@ class TestPiecewise(TestCase):
         assert_(y.ndim == 0)
         assert_(y == 0)
 
+        x = 5
+        y = piecewise(x, [[True], [False]], [1, 0])
+        assert_(y.ndim == 0)
+        assert_(y == 1)
+
+    def test_0d_comparison(self):
+        x = 3
+        y = piecewise(x, [x <= 3, x > 3], [4, 0])
+
 
 class TestBincount(TestCase):
     def test_simple(self):