Allow many distributions to have a scale of 0.

(in which case a stream of 0's is usually returned (or 1's)).

See #5818.

1 files changed, 30 insertions, 0 deletions

diff --git a/numpy/random/tests/test_random.py b/numpy/random/tests/test_random.py
index a07fa52f5..3f4952d20 100644
--- a/numpy/random/tests/test_random.py
+++ b/numpy/random/tests/test_random.py
@@ -481,6 +481,9 @@ class TestRandomDist(TestCase):
                             [0.68717433461363442, 1.69175666993575979]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_exponential_0(self):
+        assert_equal(np.random.exponential(scale=0), 0)
+
     def test_f(self):
         np.random.seed(self.seed)
         actual = np.random.f(12, 77, size=(3, 2))
@@ -497,6 +500,9 @@ class TestRandomDist(TestCase):
                             [31.71863275789960568, 33.30143302795922011]])
         assert_array_almost_equal(actual, desired, decimal=14)
 
+    def test_gamma_0(self):
+        assert_equal(np.random.gamma(shape=0, scale=0), 0)
+
     def test_geometric(self):
         np.random.seed(self.seed)
         actual = np.random.geometric(.123456789, size=(3, 2))
@@ -513,6 +519,9 @@ class TestRandomDist(TestCase):
                             [1.10651090478803416, -0.69535848626236174]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_gumbel_0(self):
+        assert_equal(np.random.gumbel(scale=0), 0)
+
     def test_hypergeometric(self):
         np.random.seed(self.seed)
         actual = np.random.hypergeometric(10.1, 5.5, 14, size=(3, 2))
@@ -547,6 +556,9 @@ class TestRandomDist(TestCase):
                             [-0.05391065675859356, 1.74901336242837324]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_laplace_0(self):
+        assert_equal(np.random.laplace(scale=0), 0)
+
     def test_logistic(self):
         np.random.seed(self.seed)
         actual = np.random.logistic(loc=.123456789, scale=2.0, size=(3, 2))
@@ -555,6 +567,9 @@ class TestRandomDist(TestCase):
                             [-0.21682183359214885, 2.63373365386060332]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_laplace_0(self):
+        assert_(np.random.laplace(scale=0) in [0, 1])
+
     def test_lognormal(self):
         np.random.seed(self.seed)
         actual = np.random.lognormal(mean=.123456789, sigma=2.0, size=(3, 2))
@@ -563,6 +578,9 @@ class TestRandomDist(TestCase):
                             [65.72798501792723869, 86.84341601437161273]])
         assert_array_almost_equal(actual, desired, decimal=13)
 
+    def test_lognormal_0(self):
+        assert_equal(np.random.lognormal(sigma=0), 1)
+
     def test_logseries(self):
         np.random.seed(self.seed)
         actual = np.random.logseries(p=.923456789, size=(3, 2))
@@ -653,6 +671,9 @@ class TestRandomDist(TestCase):
                             [4.18552478636557357, 4.46410668111310471]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_normal_0(self):
+        assert_equal(np.random.normal(scale=0), 0)
+
     def test_pareto(self):
         np.random.seed(self.seed)
         actual = np.random.pareto(a=.123456789, size=(3, 2))
@@ -700,6 +721,9 @@ class TestRandomDist(TestCase):
                             [11.06066537006854311, 17.35468505778271009]])
         assert_array_almost_equal(actual, desired, decimal=14)
 
+    def test_rayleigh_0(self):
+        assert_equal(np.random.rayleigh(scale=0), 0)
+
     def test_standard_cauchy(self):
         np.random.seed(self.seed)
         actual = np.random.standard_cauchy(size=(3, 2))
@@ -724,6 +748,9 @@ class TestRandomDist(TestCase):
                             [7.54838614231317084, 8.012756093271868]])
         assert_array_almost_equal(actual, desired, decimal=14)
 
+    def test_standard_gamma_0(self):
+        assert_equal(np.random.standard_gamma(shape=0), 0)
+
     def test_standard_normal(self):
         np.random.seed(self.seed)
         actual = np.random.standard_normal(size=(3, 2))
@@ -799,6 +826,9 @@ class TestRandomDist(TestCase):
                             [0.67057783752390987, 1.39494046635066793]])
         assert_array_almost_equal(actual, desired, decimal=15)
 
+    def test_weibull_0(self):
+        assert_equal(np.random.weibull(a=0), 0)
+
     def test_zipf(self):
         np.random.seed(self.seed)
         actual = np.random.zipf(a=1.23, size=(3, 2))