2 files changed, 92 insertions, 7 deletions
diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index 7eeed7825..d2859d94d 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -2026,7 +2026,7 @@ class vectorize:
         self.pyfunc = pyfunc
         self.cache = cache
         self.signature = signature
-        self._ufunc = None    # Caching to improve default performance
+        self._ufunc = {}    # Caching to improve default performance
 
         if doc is None:
             self.__doc__ = pyfunc.__doc__
@@ -2091,14 +2091,22 @@ class vectorize:
 
         if self.otypes is not None:
             otypes = self.otypes
-            nout = len(otypes)
 
-            # Note logic here: We only *use* self._ufunc if func is self.pyfunc
-            # even though we set self._ufunc regardless.
-            if func is self.pyfunc and self._ufunc is not None:
-                ufunc = self._ufunc
+            # self._ufunc is a dictionary whose keys are the number of
+            # arguments (i.e. len(args)) and whose values are ufuncs created
+            # by frompyfunc. len(args) can be different for different calls if
+            # self.pyfunc has parameters with default values.  We only use the
+            # cache when func is self.pyfunc, which occurs when the call uses
+            # only positional arguments and no arguments are excluded.
+
+            nin = len(args)
+            nout = len(self.otypes)
+            if func is not self.pyfunc or nin not in self._ufunc:
+                ufunc = frompyfunc(func, nin, nout)
             else:
-                ufunc = self._ufunc = frompyfunc(func, len(args), nout)
+                ufunc = None  # We'll get it from self._ufunc
+            if func is self.pyfunc:
+                ufunc = self._ufunc.setdefault(nin, ufunc)
         else:
             # Get number of outputs and output types by calling the function on
             # the first entries of args.  We also cache the result to prevent
diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
index 23bf3296d..9470a355d 100644
--- a/numpy/lib/tests/test_function_base.py
+++ b/numpy/lib/tests/test_function_base.py
@@ -1273,6 +1273,83 @@ class TestVectorize:
         r2 = np.array([3, 4, 5])
         assert_array_equal(r1, r2)
 
+    def test_keywords_with_otypes_order1(self):
+        # gh-1620: The second call of f would crash with
+        # `ValueError: invalid number of arguments`.
+
+        import math
+
+        def foo(x, y=1.0):
+            return y*math.floor(x)
+
+        f = vectorize(foo, otypes=[float])
+        r1 = f(np.arange(3.0), 1.0)
+        r2 = f(np.arange(3.0))
+        assert_array_equal(r1, r2)
+
+    def test_keywords_with_otypes_order2(self):
+        # gh-1620: The second call of f would crash with
+        # `ValueError: non-broadcastable output operand with shape ()
+        # doesn't match the broadcast shape (3,)`.
+
+        import math
+
+        def foo(x, y=1.0):
+            return y*math.floor(x)
+
+        f = vectorize(foo, otypes=[float])
+        r1 = f(np.arange(3.0))
+        r2 = f(np.arange(3.0), 1.0)
+        assert_array_equal(r1, r2)
+
+    def test_keywords_with_otypes_order3(self):
+        # gh-1620: The third call of f would crash with
+        # `ValueError: invalid number of arguments`.
+
+        import math
+
+        def foo(x, y=1.0):
+            return y*math.floor(x)
+
+        f = vectorize(foo, otypes=[float])
+        r1 = f(np.arange(3.0))
+        r2 = f(np.arange(3.0), y=1.0)
+        r3 = f(np.arange(3.0))
+        assert_array_equal(r1, r2)
+        assert_array_equal(r1, r3)
+
+    def test_keywords_with_otypes_several_kwd_args1(self):
+        # gh-1620 Make sure different uses of keyword arguments
+        # don't break the vectorized function.
+
+        import math
+
+        def foo(x, y=1.0, z=0.0):
+            return y*math.floor(x) + z
+
+        f = vectorize(foo, otypes=[float])
+        r1 = f(10.4, z=100)
+        r2 = f(10.4, y=-1)
+        r3 = f(10.4)
+        assert_equal(r1, foo(10.4, z=100))
+        assert_equal(r2, foo(10.4, y=-1))
+        assert_equal(r3, foo(10.4))
+
+    def test_keywords_with_otypes_several_kwd_args2(self):
+        # gh-1620 Make sure different uses of keyword arguments
+        # don't break the vectorized function.
+
+        import math
+
+        def foo(x, y=1.0, z=0.0):
+            return y*math.floor(x) + z
+
+        f = vectorize(foo, otypes=[float])
+        r1 = f(z=100, x=10.4, y=-1)
+        r2 = f(1, 2, 3)
+        assert_equal(r1, foo(z=100, x=10.4, y=-1))
+        assert_equal(r2, foo(1, 2, 3))
+
     def test_keywords_no_func_code(self):
         # This needs to test a function that has keywords but
         # no func_code attribute, since otherwise vectorize will