Fix histogramdd treatment of events at rightmost binedge

Fixes Github issue #4266

2 files changed, 27 insertions, 3 deletions

diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index 63b191b07..21a531211 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -373,10 +373,10 @@ def histogramdd(sample, bins=10, range=None, normed=False, weights=None):
         if not np.isinf(mindiff):
             decimal = int(-log10(mindiff)) + 6
             # Find which points are on the rightmost edge.
-            on_edge = where(around(sample[:, i], decimal) ==
-                            around(edges[i][-1], decimal))[0]
+            not_smaller_than_edge = (sample[:, i] >= edges[i][-1])
+            on_edge = (around(sample[:, i], decimal) == around(edges[i][-1], decimal))
             # Shift these points one bin to the left.
-            Ncount[i][on_edge] -= 1
+            Ncount[i][where(on_edge & not_smaller_than_edge)[0]] -= 1
 
     # Flattened histogram matrix (1D)
     # Reshape is used so that overlarge arrays
diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
index 003d3e541..82d90311e 100644
--- a/numpy/lib/tests/test_function_base.py
+++ b/numpy/lib/tests/test_function_base.py
@@ -1155,6 +1155,30 @@ class TestHistogramdd(TestCase):
             h, e = np.histogramdd(x, bins=[3, [-np.inf, 3, np.inf]])
             assert_allclose(h, expected)
 
+    def test_rightmost_binedge(self):
+        """Test event very close to rightmost binedge.
+        See Github issue #4266"""
+        x = [0.9999999995]
+        bins = [[0.,0.5,1.0]]
+        hist, _ = histogramdd(x, bins=bins)
+        assert_(hist[0] == 0.0)
+        assert_(hist[1] == 1.)
+        x = [1.0]
+        bins = [[0.,0.5,1.0]]
+        hist, _ = histogramdd(x, bins=bins)
+        assert_(hist[0] == 0.0)
+        assert_(hist[1] == 1.)
+        x = [1.0000000001]
+        bins = [[0.,0.5,1.0]]
+        hist, _ = histogramdd(x, bins=bins)
+        assert_(hist[0] == 0.0)
+        assert_(hist[1] == 1.)
+        x = [1.0001]
+        bins = [[0.,0.5,1.0]]
+        hist, _ = histogramdd(x, bins=bins)
+        assert_(hist[0] == 0.0)
+        assert_(hist[1] == 0.0)
+
 
 class TestUnique(TestCase):
     def test_simple(self):