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