-

cool-RR · cool-RR · commit b5da6bf4c145 · 2014-09-26T20:59:54.000+03:00
diff --git a/source_py3/python_toolbox/math_tools/sequences.py b/source_py3/python_toolbox/math_tools/sequences.py
@@ -63,12 +63,16 @@ def abs_stirling(n, k):
 def get_sub_counters_counter(counter):
     from python_toolbox import nifty_collections
     assert isinstance(counter, nifty_collections.FrozenCounter)
+    # d = {}
+    # for key_to_reduce, value_of_key_to_reduce in counter.items():
+        
+        # pass
     return nifty_collections.FrozenCounter({
         nifty_collections.FrozenCounter(
-            {key: (value - (key == key_to_reduce)) for
+            {(key - (key == key_to_reduce)): value for
                                                  key, value in counter.items()}
         ): value_of_key_to_reduce
-                   for key_to_reduce, value_of_key_to_reduce in counter.items()
+                   
     })
     
 
diff --git a/source_py3/python_toolbox/math_tools/types.py b/source_py3/python_toolbox/math_tools/types.py
@@ -22,4 +22,9 @@ class PossiblyInfiniteReal(numbers.Number,
                            metaclass=_PossiblyInfiniteRealType):
     pass
 
-
+class _NaturalType(abc.ABCMeta):
+    def __instancecheck__(self, thing):
+        return isinstance(thing, numbers.Integral) and thing >= 1
+class Natural(numbers.Number,
+              metaclass=_NaturalType):
+    pass
diff --git a/source_py3/python_toolbox/nifty_collections/frozen_chunk_counter.py b/source_py3/python_toolbox/nifty_collections/frozen_chunk_counter.py
@@ -0,0 +1,20 @@
+# Copyright 2009-2014 Ram Rachum.,
+# This program is distributed under the MIT license.
+
+from python_toolbox import math_tools
+
+from .frozen_counter import FrozenCounter
+
+
+class FrozenChunkCounter(FrozenCounter):
+    def __init__(self, iterable):
+        super().__init__()
+        
+        # All zero values were already fileterd out by `FrozenCounter`, we'll
+        # filter out just the non-natural-number keys.
+        for key in [key for key in self if not isinstance(key, math_tools.Natural)]:
+            if key == 0:
+                del self._dict[key]
+            else:
+                raise TypeError('Keys to `FrozenChunkCounter` must be '
+                                'non-negative integers.')
