1 files changed, 39 insertions, 7 deletions
diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index 7eeed7825..dea01d12d 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -764,6 +764,30 @@ def copy(a, order='K', subok=False):
     >>> x[0] == z[0]
     False
 
+    Note that np.copy is a shallow copy and will not copy object
+    elements within arrays. This is mainly important for arrays
+    containing Python objects. The new array will contain the
+    same object which may lead to surprises if that object can
+    be modified (is mutable):
+
+    >>> a = np.array([1, 'm', [2, 3, 4]], dtype=object)
+    >>> b = np.copy(a)
+    >>> b[2][0] = 10
+    >>> a
+    array([1, 'm', list([10, 3, 4])], dtype=object)
+
+    To ensure all elements within an ``object`` array are copied,
+    use `copy.deepcopy`:
+
+    >>> import copy
+    >>> a = np.array([1, 'm', [2, 3, 4]], dtype=object)
+    >>> c = copy.deepcopy(a)
+    >>> c[2][0] = 10
+    >>> c
+    array([1, 'm', list([10, 3, 4])], dtype=object)
+    >>> a
+    array([1, 'm', list([2, 3, 4])], dtype=object)
+
     """
     return array(a, order=order, subok=subok, copy=True)
 
@@ -2026,7 +2050,7 @@ 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 +2115,22 @@ 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