ENH: np.random.default_gen() (#13840)

* ENH: Rename seed_seq argument to seed and replace Generator() with default_gen()

2 files changed, 61 insertions, 1 deletions

diff --git a/numpy/random/tests/test_direct.py b/numpy/random/tests/test_direct.py
index 1e824fbcc..97cec6e26 100644
--- a/numpy/random/tests/test_direct.py
+++ b/numpy/random/tests/test_direct.py
@@ -7,7 +7,8 @@ from numpy.testing import (assert_equal, assert_allclose, assert_array_equal,
 import pytest
 
 from numpy.random import (
-  Generator, MT19937, PCG64, Philox, RandomState, SeedSequence, SFC64
+    Generator, MT19937, PCG64, Philox, RandomState, SeedSequence, SFC64,
+    default_gen
 )
 from numpy.random.common import interface
 
@@ -400,3 +401,18 @@ class TestSFC64(Base):
         cls.seed_error_type = (ValueError, TypeError)
         cls.invalid_init_types = [(3.2,), ([None],), (1, None)]
         cls.invalid_init_values = [(-1,)]
+
+
+class TestDefaultGen(object):
+    def test_seed(self):
+        for args in [(), (None,), (1234,), ([1234, 5678],)]:
+            rg = default_gen(*args)
+            assert isinstance(rg.bit_generator, PCG64)
+
+    def test_passthrough(self):
+        bg = Philox()
+        rg = default_gen(bg)
+        assert rg.bit_generator is bg
+        rg2 = default_gen(rg)
+        assert rg2 is rg
+        assert rg2.bit_generator is bg
diff --git a/numpy/random/tests/test_smoke.py b/numpy/random/tests/test_smoke.py
index 4263335f6..12feec098 100644
--- a/numpy/random/tests/test_smoke.py
+++ b/numpy/random/tests/test_smoke.py
@@ -764,6 +764,50 @@ class TestSFC64(RNG):
         cls._extra_setup()
 
 
+class TestPCG64(RNG):
+    @classmethod
+    def setup_class(cls):
+        cls.bit_generator = PCG64
+        cls.advance = 2**63 + 2**31 + 2**15 + 1
+        cls.seed = [12345]
+        cls.rg = Generator(cls.bit_generator(*cls.seed))
+        cls.initial_state = cls.rg.bit_generator.state
+        cls.seed_vector_bits = 64
+        cls._extra_setup()
+
+
+class TestDefaultGen(RNG):
+    @classmethod
+    def setup_class(cls):
+        # This will duplicate some tests that directly instantiate a fresh
+        # Generator(), but that's okay.
+        cls.bit_generator = PCG64
+        cls.advance = 2**63 + 2**31 + 2**15 + 1
+        cls.seed = [12345]
+        cls.rg = np.random.default_gen(*cls.seed)
+        cls.initial_state = cls.rg.bit_generator.state
+        cls.seed_vector_bits = 64
+        cls._extra_setup()
+
+    def test_default_is_pcg64(self):
+        # In order to change the default BitGenerator, we'll go through
+        # a deprecation cycle to move to a different function.
+        assert_(isinstance(self.rg.bit_generator, PCG64))
+
+    def test_seed(self):
+        np.random.default_gen()
+        np.random.default_gen(None)
+        np.random.default_gen(12345)
+        np.random.default_gen(0)
+        np.random.default_gen(43660444402423911716352051725018508569)
+        np.random.default_gen([43660444402423911716352051725018508569,
+                               279705150948142787361475340226491943209])
+        with pytest.raises(ValueError):
+            np.random.default_gen(-1)
+        with pytest.raises(ValueError):
+            np.random.default_gen([12345, -1])
+
+
 class TestEntropy(object):
     def test_entropy(self):
         e1 = entropy.random_entropy()