Bring back the 2-arg form of cycler() and __repr__

Author: WeatherGod

cycler.py

@@ -164,8 +164,8 @@ def __getitem__(self, key):
         # TODO : maybe add numpy style fancy slicing
         if isinstance(key, slice):
             trans = self._transpose()
-            return cycler(**dict((k, v[key])
-                                 for k, v in six.iteritems(trans)))
+            return reduce(add, (_cycler(k, v[key])
+                                for k, v in six.iteritems(trans)))
         else:
             raise ValueError("Can only use slices with Cycler.__getitem__")
 
@@ -203,8 +203,8 @@ def __mul__(self, other):
             return Cycler(self, other, product)
         elif isinstance(other, int):
             trans = self._transpose()
-            return cycler(**dict((k, v*other)
-                                 for k, v in six.iteritems(trans)))
+            return reduce(add, (_cycler(k, v*other)
+                                for k, v in six.iteritems(trans)))
         else:
             return NotImplemented
 
@@ -268,7 +268,7 @@ def __repr__(self):
         if self._right is None:
             lab = self.keys.pop()
             itr = list(v[lab] for v in self)
-            return "cycler({lab}={itr!r})".format(lab=lab, itr=itr)
+            return "cycler({lab!r}, {itr!r})".format(lab=lab, itr=itr)
         else:
             op = op_map.get(self._op, '?')
             msg = "({left!r} {op} {right!r})"
@@ -329,7 +329,7 @@ def simplify(self):
         # I would believe that there is some performance implications
 
         trans = self._transpose()
-        return cycler(**dict((k, v) for k, v in six.iteritems(trans)))
+        return reduce(add, (_cycler(k, v) for k, v in six.iteritems(trans)))
 
 
 def cycler(*args, **kwargs):
@@ -339,15 +339,19 @@ def cycler(*args, **kwargs):
 
     cycler(arg)
     cycler(label1=itr1[, label2=iter2[, ...]])
+    cycler(label, itr)
 
     Form 1 simply copies a given `Cycler` object.
     Form 2 composes a `Cycler` as an inner product of the
     pairs of keyword arguments.
+    Form 3 creates a `Cycler` from a label and an iterable.
+    This is useful for when the label cannot be a keyword argument.
 
     Parameters
     ----------
-    label : str
-        The property key.
+    label : name
+        The property key. In the 2-arg form of the function,
+        the label can be any hashable object.
 
     itr : iterable
         Finite length iterable of the property values.
@@ -367,7 +371,9 @@ def cycler(*args, **kwargs):
             raise TypeError("If only one positional argument given, it must "
                             " be a Cycler instance.")
         return copy.copy(args[0])
-    elif len(args) > 1:
+    elif len(args) == 2:
+        return _cycler(*args)
+    elif len(args) > 2:
         raise TypeError("Only a single Cycler can be accepted as the lone "
                         "positional argument. Use keyword arguments instead.")
 

test_cycler.py

@@ -74,6 +74,9 @@ def test_constructor():
     yield _cycler_helper, c1+c2, 3, ['c', 'ec'], [['r', 'g', 'b']]*2
     c3 = cycler(c=c1)
     yield _cycler_helper, c3+c2, 3, ['c', 'ec'], [['r', 'g', 'b']]*2
+    # Using a non-string hashable
+    c4 = cycler(1, range(3))
+    yield _cycler_helper, c4+c1, 3, [1, 'c'], [range(3), ['r', 'g', 'b']]
 
     # addition using cycler()
     yield (_cycler_helper, cycler(c='rgb', lw=range(3)),
@@ -123,13 +126,13 @@ def test_mul_fails():
 
 
 def test_getitem():
-    c1 = cycler(lw=range(15))
+    c1 = cycler(3, range(15))
     widths = list(range(15))
     for slc in (slice(None, None, None),
                 slice(None, None, -1),
                 slice(1, 5, None),
                 slice(0, 5, 2)):
-        yield _cycles_equal, c1[slc], cycler(lw=widths[slc])
+        yield _cycles_equal, c1[slc], cycler(3, widths[slc])
 
 
 def test_fail_getime():
@@ -147,16 +150,17 @@ def _repr_tester_helper(rpr_func, cyc, target_repr):
 
 def test_repr():
     c = cycler(c='rgb')
-    c2 = cycler(lw=range(3))
+    # Using an identifier that would be not valid as a kwarg
+    c2 = cycler('3rd', range(3))
 
-    c_sum_rpr = "(cycler(c=['r', 'g', 'b']) + cycler(lw=[0, 1, 2]))"
-    c_prod_rpr = "(cycler(c=['r', 'g', 'b']) * cycler(lw=[0, 1, 2]))"
+    c_sum_rpr = "(cycler('c', ['r', 'g', 'b']) + cycler('3rd', [0, 1, 2]))"
+    c_prod_rpr = "(cycler('c', ['r', 'g', 'b']) * cycler('3rd', [0, 1, 2]))"
 
     yield _repr_tester_helper, '__repr__', c + c2, c_sum_rpr
     yield _repr_tester_helper, '__repr__', c * c2, c_prod_rpr
 
-    sum_html = "<table><th>'c'</th><th>'lw'</th><tr><td>'r'</td><td>0</td></tr><tr><td>'g'</td><td>1</td></tr><tr><td>'b'</td><td>2</td></tr></table>"
-    prod_html = "<table><th>'c'</th><th>'lw'</th><tr><td>'r'</td><td>0</td></tr><tr><td>'r'</td><td>1</td></tr><tr><td>'r'</td><td>2</td></tr><tr><td>'g'</td><td>0</td></tr><tr><td>'g'</td><td>1</td></tr><tr><td>'g'</td><td>2</td></tr><tr><td>'b'</td><td>0</td></tr><tr><td>'b'</td><td>1</td></tr><tr><td>'b'</td><td>2</td></tr></table>"
+    sum_html = "<table><th>'3rd'</th><th>'c'</th><tr><td>0</td><td>'r'</td></tr><tr><td>1</td><td>'g'</td></tr><tr><td>2</td><td>'b'</td></tr></table>"
+    prod_html = "<table><th>'3rd'</th><th>'c'</th><tr><td>0</td><td>'r'</td></tr><tr><td>1</td><td>'r'</td></tr><tr><td>2</td><td>'r'</td></tr><tr><td>0</td><td>'g'</td></tr><tr><td>1</td><td>'g'</td></tr><tr><td>2</td><td>'g'</td></tr><tr><td>0</td><td>'b'</td></tr><tr><td>1</td><td>'b'</td></tr><tr><td>2</td><td>'b'</td></tr></table>"
 
     yield _repr_tester_helper, '_repr_html_', c + c2, sum_html
     yield _repr_tester_helper, '_repr_html_', c * c2, prod_html