update from Atlas

attic/iterables/almost_aritprog_v0.py

@@ -0,0 +1,38 @@
+"""
+Arithmetic progression class
+
+    >>> ap = ArithmeticProgression(1, .5, 3)
+    >>> list(ap)
+    [1.0, 1.5, 2.0, 2.5]
+
+
+"""
+
+from collections import abc
+
+
+class ArithmeticProgression:
+
+    def __init__(self, begin, step, end):
+        self.begin = begin
+        self.step = step
+        self.end = end
+
+    def __iter__(self):
+        return ArithmeticProgressionIterator(self)
+
+
+class ArithmeticProgressionIterator(abc.Iterator):
+
+    def __init__(self, arithmetic_progression):
+        self._ap = arithmetic_progression
+        self._index = 0
+
+    def __next__(self):
+        first = type(self._ap.begin + self._ap.step)(self._ap.begin)
+        result = first + self._ap.step * self._index
+        if result < self._ap.end:
+            self._index += 1
+            return result
+        else:
+            raise StopIteration