update from Atlas

14-it-generator/aritprog_v1.py

@@ -0,0 +1,44 @@
+"""
+Arithmetic progression class
+
+# BEGIN ARITPROG_CLASS_DEMO
+
+    >>> ap = ArithmeticProgression(0, 1, 3)
+    >>> list(ap)
+    [0, 1, 2]
+    >>> ap = ArithmeticProgression(1, .5, 3)
+    >>> list(ap)
+    [1.0, 1.5, 2.0, 2.5]
+    >>> ap = ArithmeticProgression(0, 1/3, 1)
+    >>> list(ap)
+    [0.0, 0.3333333333333333, 0.6666666666666666]
+    >>> from fractions import Fraction
+    >>> ap = ArithmeticProgression(0, Fraction(1, 3), 1)
+    >>> list(ap)
+    [Fraction(0, 1), Fraction(1, 3), Fraction(2, 3)]
+    >>> from decimal import Decimal
+    >>> ap = ArithmeticProgression(0, Decimal('.1'), .3)
+    >>> list(ap)
+    [Decimal('0.0'), Decimal('0.1'), Decimal('0.2')]
+
+# END ARITPROG_CLASS_DEMO
+"""
+
+
+# BEGIN ARITPROG_CLASS
+class ArithmeticProgression:
+
+    def __init__(self, begin, step, end=None):  # <1>
+        self.begin = begin
+        self.step = step
+        self.end = end  # None -> "infinite" series
+
+    def __iter__(self):
+        result = type(self.begin + self.step)(self.begin)  # <2>
+        forever = self.end is None  # <3>
+        index = 0
+        while forever or result < self.end:  # <4>
+            yield result  # <5>
+            index += 1
+            result = self.begin + self.step * index  # <6>
+# END ARITPROG_CLASS