Python 列表推导、迭代器与生成器

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 self   for 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 + b fib = fibonacci() print([next(fib) for i in range(10)]) # >=python 3.0 print(fib.__next__() for i in range(10)]) # >=python 3.0 print(fib.next() for i in range(10)]) # <python 3.0

来自为知笔记(Wiz)