BUG: Always return a list from np.ma.flatnotmasked_contiguous

Depending on the input, this would return:
* A single slice, if mask=nomask
* A list of slices, if mask is an array
* None, if mask is fully masked

The documented return value is a list, and all downstream callers of this
function end up having to correct for it not being one.

This affects the result of np.ma.notmasked_contiguous, which also did not
document these unusual return values.

1 files changed, 7 insertions, 4 deletions

diff --git a/numpy/ma/tests/test_extras.py b/numpy/ma/tests/test_extras.py
index 9bebd6145..95319eb65 100644
--- a/numpy/ma/tests/test_extras.py
+++ b/numpy/ma/tests/test_extras.py
@@ -128,7 +128,10 @@ class TestGeneric(object):
         a = arange(10)
         # No mask
         test = flatnotmasked_contiguous(a)
-        assert_equal(test, slice(0, a.size))
+        assert_equal(test, [slice(0, a.size)])
+        # mask of all false
+        a.mask = np.zeros(10, dtype=bool)
+        assert_equal(test, [slice(0, a.size)])
         # Some mask
         a[(a < 3) | (a > 8) | (a == 5)] = masked
         test = flatnotmasked_contiguous(a)
@@ -136,7 +139,7 @@ class TestGeneric(object):
         #
         a[:] = masked
         test = flatnotmasked_contiguous(a)
-        assert_equal(test, None)
+        assert_equal(test, [])
 
 
 class TestAverage(object):
@@ -384,14 +387,14 @@ class TestNotMasked(object):
             [slice(0, 1, None), slice(2, 3, None)],
             [slice(2, 3, None)],
             [slice(2, 3, None)],
-            None,
+            [],
             [slice(2, 3, None)]
         ])
         #
         tmp = notmasked_contiguous(a, 1)
         assert_equal(tmp, [
             [slice(0, 4, None)],
-            None,
+            [],
             [slice(0, 6, None), slice(7, 8, None)]
         ])