Merge pull request #13655 from bashtage/integer-byteorder

BUG/MAINT: Non-native byteorder in random ints

4 files changed, 29 insertions, 4 deletions

diff --git a/numpy/random/generator.pyx b/numpy/random/generator.pyx
index ca5d4293c..fd93d5efe 100644
--- a/numpy/random/generator.pyx
+++ b/numpy/random/generator.pyx
@@ -429,9 +429,15 @@ cdef class Generator:
             high = low
             low = 0
 
-        key = np.dtype(dtype).name
+        dt = np.dtype(dtype)
+        key = dt.name
         if key not in _integers_types:
             raise TypeError('Unsupported dtype "%s" for integers' % key)
+        if not dt.isnative:
+            raise ValueError('Providing a dtype with a non-native byteorder '
+                             'is not supported. If you require '
+                             'platform-independent byteorder, call byteswap '
+                             'when required.')
 
         # Implementation detail: the old API used a masked method to generate
         # bounded uniform integers. Lemire's method is preferrable since it is
diff --git a/numpy/random/mtrand.pyx b/numpy/random/mtrand.pyx
index f1d45668e..a1364ac18 100644
--- a/numpy/random/mtrand.pyx
+++ b/numpy/random/mtrand.pyx
@@ -606,9 +606,17 @@ cdef class RandomState:
             high = low
             low = 0
 
-        key = np.dtype(dtype).name
+        dt = np.dtype(dtype)
+        key = dt.name
         if key not in _integers_types:
             raise TypeError('Unsupported dtype "%s" for randint' % key)
+        if not dt.isnative:
+            # numpy 1.17.0, 2019-05-28
+            warnings.warn('Providing a dtype with a non-native byteorder is '
+                          'not supported. If you require platform-independent '
+                          'byteorder, call byteswap when required.\nIn future '
+                          'version, providing byteorder will raise a '
+                          'ValueError', DeprecationWarning)
 
         # Implementation detail: the use a masked method to generate
         # bounded uniform integers. Lemire's method is preferrable since it is
@@ -4272,5 +4280,3 @@ __all__ = [
     'zipf',
     'RandomState',
 ]
-
-
diff --git a/numpy/random/tests/test_generator_mt19937.py b/numpy/random/tests/test_generator_mt19937.py
index 192dcce08..64d87cd71 100644
--- a/numpy/random/tests/test_generator_mt19937.py
+++ b/numpy/random/tests/test_generator_mt19937.py
@@ -467,6 +467,10 @@ class TestIntegers(object):
             assert_equal(random.integers(0, -10, size=0).shape, (0,))
             assert_equal(random.integers(10, 10, size=0).shape, (0,))
 
+    def test_error_byteorder(self):
+        other_byteord_dt = '<i4' if sys.byteorder == 'big' else '>i4'
+        with pytest.raises(ValueError):
+            random.integers(0, 200, size=10, dtype=other_byteord_dt)
 
 class TestRandomDist(object):
     # Make sure the random distribution returns the correct value for a
diff --git a/numpy/random/tests/test_randomstate_regression.py b/numpy/random/tests/test_randomstate_regression.py
index 9c319319e..5bb1ddde5 100644
--- a/numpy/random/tests/test_randomstate_regression.py
+++ b/numpy/random/tests/test_randomstate_regression.py
@@ -1,4 +1,7 @@
 import sys
+
+import pytest
+
 from numpy.testing import (
     assert_, assert_array_equal, assert_raises,
     )
@@ -155,3 +158,9 @@ class TestRegression(object):
         perm = random.permutation(m)
         assert_array_equal(perm, np.array([2, 1, 4, 0, 3]))
         assert_array_equal(m.__array__(), np.arange(5))
+
+    def test_warns_byteorder(self):
+        # GH 13159
+        other_byteord_dt = '<i4' if sys.byteorder == 'big' else '>i4'
+        with pytest.deprecated_call(match='non-native byteorder is not'):
+            random.randint(0, 200, size=10, dtype=other_byteord_dt)