1、列表推导
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numbers = [i for i in range(10) if i % 2 == 0]print(numbers)seq = ["one", "two", "three"]for i, element in enumerate(seq): print(i, element)def treatment(pos, element): return ('%d: %s' % (pos, element))print ([treatment(i, element) for i, element in enumerate(seq)]) |
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enumerate(sequence, [start=0])Return an enumerate object. sequence must be a sequence, an iterator, or some other object which supports iteration. The next() method of the iterator returned by enumerate() returns a tuple containing a count (from start which defaults to 0) and the corresponding value obtained from iterating over iterable. enumerate() is useful for obtaining an indexed series: (0, seq[0]), (1, seq[1]), (2,seq[2]), .... |
2、迭代器
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class MyIterator(object): def __init__(self, step): self.step = step def __next__(self): # 3.0之后一般采用该样式 if self.step == 0: raise StopIteration self.step -= 1 return self.step def __iter__(self): return selffor i in MyIterator(5): print(i) |
3、生成器
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def fibonacci(): a, b = 0, 1 while True: yield b a, b = b, a + bfib = fibonacci()print([next(fib) for i in range(10)]) # >=python 3.0print(fib.__next__() for i in range(10)]) # >=python 3.0print(fib.next() for i in range(10)]) # <python 3.0 |