Merge pull request #5380 from happygds/happygds-patch-1

theano/tensor/basic.py

@@ -4219,6 +4219,9 @@ def roll(x, shift, axis=None):
         else:
             axis = 0
 
+    if axis < 0:
+        axis += x.ndim
+
     # Shift may be larger than the size of the axis. If so, since the
     # roll operation is cyclic, we can take the shift modulo the size
     # of the axis

theano/tensor/tests/test_basic.py

@@ -3838,6 +3838,15 @@ class T_Join_and_Split(unittest.TestCase):
             want = numpy.roll(a.get_value(borrow=True), -2, 1)
             out = theano.function([], b)()
 
+            assert (out == want).all()
+                
+            # Test example when axis < 0 - ensure that behavior matches numpy.roll behavior
+            a = self.shared(numpy.arange(24).reshape((3, 2, 4)).astype(self.floatX))
+            b = roll(a, get_shift(-2), -2)
+
+            want = numpy.roll(a.get_value(borrow=True), -2, -2)
+            out = theano.function([], b)()
+
             assert (out == want).all()
 
             # Test rolling on axis 0