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  • 列表推导式、字典推导式、set推导式

    一、列表推导式

    语法:[表达式  for循环  if判断]

    list = [i for i in range(1,11)]
    print(list)

    结果:

    list = [i +1 for i in range(10)]
    print(list)

    结果:

     示例:生成1-10之间的偶数列表

    list = [i for i in range(11) if i%2==0]
    print(list)

    结果:

     示例:生成一个含有10个元素的列表,10个元素都是666

    list = [666 for i in range(10)]
    print(list)

    结果:

     如果for循环中的i不使用,用下划线代替,下划线表示没有用的参数

    list = [666 for _ in range(10)]
    print(list)

    示例:过滤掉名字长度小于5的

    list1 = ["zhangsan","lisi","wangwu"]
    list2 = [name for name in list1 if len(name) > 5]
    print(list2)

    注意:for循环中不一定要用到range。

     2个for循环

    list = [(x,y) for x in range(1,3) for y in range(3)]
    print(list)

    结果:

     二、字典推导式

    格式:{key : value  for循环  if判断}

    dict = { str(i) : i**2 for i in range(1,11)}
    print(dict)

    结果:

     示例:将key和value互换位置

    dict = {"name": "zhangsan","age": 18}
    dict1 = {dict[key]: key for key in dict}
    print(dict1)

    结果:

     三、无序集合推导式

     无序集合可以去重

    语法:{表达式  for循环  if判断}

    list = ["beijing","shanghai","beijing"]
    list1 = {city for city in list if city.startswith("b")}
    print(list1)

    结果:

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  • 原文地址:https://www.cnblogs.com/zwh0910/p/15251985.html
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