76 lines
1.7 KiB
Python
76 lines
1.7 KiB
Python
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"""
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迭代器 - __iter__ / __next__
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itertools - 生成可迭代序列的工具模块
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"""
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import itertools
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from math import sqrt
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def is_prime(num):
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"""判断素数"""
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for factor in range(2, int(sqrt(num)) + 1):
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if num % factor == 0:
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return False
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return True
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class PrimeIter(object):
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"""素数迭代器"""
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def __init__(self, min_value, max_value):
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assert 2 <= min_value <= max_value
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self.min_value = min_value - 1
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self.max_value = max_value
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def __iter__(self):
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return self
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def __next__(self):
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self.min_value += 1
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while self.min_value <= self.max_value:
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if is_prime(self.min_value):
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return self.min_value
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self.min_value += 1
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raise StopIteration()
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class FibIter(object):
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"""斐波那契数迭代器"""
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def __init__(self, num):
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self.num = num
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self.a, self.b = 0, 1
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self.idx = 0
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def __iter__(self):
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return self
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def __next__(self):
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if self.idx < self.num:
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self.a, self.b = self.b, self.a + self.b
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self.idx += 1
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return self.a
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raise StopIteration()
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def main():
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# for val in itertools.permutations('ABCD'):
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# print(val)
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# for val in itertools.combinations('ABCDE', 3):
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# print(val)
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# for val in itertools.product('黑红梅方', range(1, 14)):
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# print(val)
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# fib_iter = FibIter(20)
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# print('===>', next(fib_iter))
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# print('===>', next(fib_iter))
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# for val in fib_iter:
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# print(val)
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prime_iter = PrimeIter(2, 100000)
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for val in prime_iter:
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print(val)
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if __name__ == '__main__':
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main()
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