Remove dependency on six.

Mostly so that Matplotlib doesn't depend *transitively* on six either :)

- six.iteritems() -> dict.items(): OK even on Py2, we directly consume
  the iterator/list with reduce anyways, and I doubt that the perfomance
  change is measurable.
- six.moves.zip() could have been replaced with builtin zip() on both
  Py2 and Py3 because we always exhaust the iterator immediately
  anyways, but it also acts as a lookup key in `Cycler.__len__` so I
  decided to just play it safe and have a conditional import (on Py2,
  six.moves.zip is an alias for itertools.zip).

Also added new .pytest_cache directory to gitignore.

.gitignore

@@ -33,6 +33,7 @@ htmlcov/
 cover/
 .coverage
 .cache
+.pytest_cache
 nosetests.xml
 coverage.xml
 cover/

.travis.yml

@@ -13,7 +13,7 @@ matrix:
 
 install:
   - python setup.py install
-  - pip install pytest pytest-cov coverage six
+  - pip install pytest pytest-cov coverage
 
 script:
   - coverage run run_tests.py

appveyor.yml

@@ -20,7 +20,7 @@ install:
   - "python -c \"import struct; print(struct.calcsize('P') * 8)\""
 
   # Install the build and runtime dependencies of the project.
-  - "pip install -v six nose pytest pytest-cov coverage"
+  - "pip install -v nose pytest pytest-cov coverage"
 
   # Install the generated wheel package to test it
   - "python setup.py install"

conda-recipe/meta.yaml

@@ -30,11 +30,9 @@ requirements:
   build:
     - python
     - setuptools
-    - six
 
   run:
     - python
-    - six
 
 test:
   # Python imports

cycler.py

@@ -43,11 +43,14 @@
 from __future__ import (absolute_import, division, print_function,
                         unicode_literals)
 
-import six
+import copy
+from functools import reduce
 from itertools import product, cycle
-from six.moves import zip, reduce
 from operator import mul, add
-import copy
+import sys
+
+if sys.version_info < (3,):
+    from itertools import izip as zip
 
 __version__ = '0.10.0'
 
@@ -183,7 +186,6 @@ def change_key(self, old, new):
     def _compose(self):
         """
         Compose the 'left' and 'right' components of this cycle
-        with the proper operation (zip or product as of now)
         """
         for a, b in self._op(self._left, self._right):
             out = dict()
@@ -220,8 +222,7 @@ def __getitem__(self, key):
         # TODO : maybe add numpy style fancy slicing
         if isinstance(key, slice):
             trans = self.by_key()
-            return reduce(add, (_cycler(k, v[key])
-                                for k, v in six.iteritems(trans)))
+            return reduce(add, (_cycler(k, v[key]) for k, v in trans.items()))
         else:
             raise ValueError("Can only use slices with Cycler.__getitem__")
 
@@ -259,8 +260,7 @@ def __mul__(self, other):
             return Cycler(self, other, product)
         elif isinstance(other, int):
             trans = self.by_key()
-            return reduce(add, (_cycler(k, v*other)
-                                for k, v in six.iteritems(trans)))
+            return reduce(add, (_cycler(k, v*other) for k, v in trans.items()))
         else:
             return NotImplemented
 
@@ -396,7 +396,7 @@ def simplify(self):
         # I would believe that there is some performance implications
 
         trans = self.by_key()
-        return reduce(add, (_cycler(k, v) for k, v in six.iteritems(trans)))
+        return reduce(add, (_cycler(k, v) for k, v in trans.items()))
 
     def concat(self, other):
         """Concatenate this cycler and an other.
@@ -523,7 +523,7 @@ def cycler(*args, **kwargs):
                         "positional argument. Use keyword arguments instead.")
 
     if kwargs:
-        return reduce(add, (_cycler(k, v) for k, v in six.iteritems(kwargs)))
+        return reduce(add, (_cycler(k, v) for k, v in kwargs.items()))
 
     raise TypeError("Must have at least a positional OR keyword arguments")
 

setup.py

@@ -8,7 +8,6 @@
       description='Composable style cycles',
       url='https://github.com/matplotlib/cycler',
       platforms='Cross platform (Linux, Mac OSX, Windows)',
-      install_requires=['six'],
       license="BSD",
       python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
       classifiers=['Development Status :: 4 - Beta',

test_cycler.py

@@ -1,12 +1,18 @@
 from __future__ import (absolute_import, division, print_function)
 
-import six
-from six.moves import zip, range
-from cycler import cycler, Cycler, concat
-import pytest
-from itertools import product, cycle, chain
-from operator import add, iadd, mul, imul
 from collections import defaultdict
+from operator import add, iadd, mul, imul
+from itertools import product, cycle, chain
+import sys
+
+import pytest
+
+from cycler import cycler, Cycler, concat
+
+if sys.version_info < (3,):
+    from itertools import izip as zip
+    range = xrange
+    str = unicode
 
 
 def _cycler_helper(c, length, keys, values):
@@ -147,7 +153,7 @@ def test_fail_getime():
 def _repr_tester_helper(rpr_func, cyc, target_repr):
     test_repr = getattr(cyc, rpr_func)()
 
-    assert six.text_type(test_repr) == six.text_type(target_repr)
+    assert str(test_repr) == str(target_repr)
 
 
 def test_repr():