matplotlib
diff --git a/‎lib/matplotlib/__init__.py
Lines changed: 15 additions & 4 deletions b/‎lib/matplotlib/__init__.py
Lines changed: 15 additions & 4 deletions
diff --git a/‎lib/matplotlib/cbook.py
Lines changed: 10 additions & 2 deletions b/‎lib/matplotlib/cbook.py
Lines changed: 10 additions & 2 deletions
diff --git a/‎lib/matplotlib/tests/test_cbook.py
Lines changed: 12 additions & 0 deletions b/‎lib/matplotlib/tests/test_cbook.py
Lines changed: 12 additions & 0 deletions
@@ -119,7 +119,10 @@
 import functools
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
-from matplotlib.cbook import is_string_like, mplDeprecation, dedent, get_label
+from matplotlib.cbook import (is_string_like,
+                              mplDeprecation,
+                              dedent, get_label,
+                              asSequence)
 from matplotlib.compat import subprocess
 from matplotlib.rcsetup import (defaultParams,
                                 validate_backend,
@@ -1641,12 +1644,15 @@ def test(verbosity=1, coverage=False):
 
 
 def _replacer(data, key):
+    """Either returns data[key] or passes data back. Also
+    converts input data to a sequence as needed.
+    """
     # if key isn't a string don't bother
     if not isinstance(key, six.string_types):
-        return key
+        return asSequence(key)
     # try to use __getitem__
     try:
-        return data[key]
+        return asSequence(data[key])
     # key does not exist, silently fall back to key
     except KeyError:
         return key
@@ -1699,6 +1705,8 @@ def foo(ax, *args, **kwargs)
         NOTE: callables should only be used when the names and order of *args
         can only be determined at runtime. Please use list of names
         when the order and names of *args is clear before runtime!
+
+    .. note:: decorator also converts MappingView input data to list.
     """
     if replace_names is not None:
         replace_names = set(replace_names)
@@ -1839,7 +1847,10 @@ def inner(ax, *args, **kwargs):
             label = None
 
             data = kwargs.pop('data', None)
-            if data is not None:
+
+            if data is None:  # data validation
+                args = tuple(asSequence(a) for a in args)
+            else:
                 if arg_names_at_runtime:
                     # update the information about replace names and
                     # label position
 
@@ -16,7 +16,7 @@
 
 import datetime
 import errno
-from functools import reduce
+import functools
 import glob
 import gzip
 import io
@@ -1758,7 +1758,7 @@ def delete_masked_points(*args):
             except:  # Fixme: put in tuple of possible exceptions?
                 pass
     if len(masks):
-        mask = reduce(np.logical_and, masks)
+        mask = functools.reduce(np.logical_and, masks)
         igood = mask.nonzero()[0]
         if len(igood) < nrecs:
             for i, x in enumerate(margs):
@@ -2445,6 +2445,14 @@ def safe_first_element(obj):
     return next(iter(obj))
 
 
+def asSequence(data):
+    """Converts dictview object to list
+    """
+    if six.PY3 and isinstance(data, collections.abc.MappingView):
+        return list(data)
+    return data
+
+
 def normalize_kwargs(kw, alias_mapping=None, required=(), forbidden=(),
                      allowed=None):
     """Helper function to normalize kwarg inputs
 
@@ -332,6 +332,18 @@ def dummy(self):
         pass
 
 
+def test_asSequence():
+    d = {'a': 1, 'b': 2, 'c': 3}
+    k = ['a', 'b', 'c']
+    v = [1, 2, 3]
+    i = [('a', 1), ('b', 2), ('c', 3)]
+    assert k == sorted(cbook.asSequence(d.keys()))
+    assert v == sorted(cbook.asSequence(d.values()))
+    assert i == sorted(cbook.asSequence(d.items()))
+    assert i == cbook.asSequence(i)
+    assert k == cbook.asSequence(k)
+
+
 def _kwarg_norm_helper(inp, expected, kwargs_to_norm, warn_count=0):
 
     with warnings.catch_warnings(record=True) as w: