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  • Python开发——4.集合和字符串拼接

    一、集合(set)

    1.集合的特性:

      不同元素组成、元素是无序排列的可hash值

    2.集合转为列表

    s1 = {11,"hechouzi",(11,22,33)}
    names = list(s1)
    print(names)

    3.集合的方法

    (1)add 添加元素

    s = {11,22,(1,2),"hechouzi"}
    s.add("kobe")
    print(s)

    (2) clear 清空元素

    s = {11,22,(1,2),"hechouzi"}
    s.clear()
    print(s)

    (3) copy

    s = {11,22,(1,2),"hechouzi"}
    s1 = s.copy()
    print(s1)

    (4)pop 随机删除,remove 指定删除,没有报错 discard 指定删除,没有不会报错

    s = {11,22,(1,2),"hechouzi"}
    s.pop()
    s.remove(11)
    s.discard(10)
    print(s)

    4.关系测试

    (1)intersection(&)求取交集

    s1 = {11,22,33,"hechouzi"}
    s2 = {22,33,"kobe"}
    # s3 = s1.intersection(s2)
    s3 = s1 & s2
    print(s3)

    (2)union(|) 求取并集

    s1 = {11,22,33,"hechouzi"}
    s2 = {22,33,"kobe"}
    # s3 = s1.union(s2)
    s3 = s1 | s2
    print(s3)

    (3) difference(-)求取差集

    s1 = {11,22,33,"hechouzi"}
    s2 = {22,33,"kobe"}
    # s3 = s1.difference(s2)
    s3 = s1 - s2
    print(s3)

    (4)symmetric_difference(^)求取交叉补集

    s1 = {11,22,33,"hechouzi"}
    s2 = {22,33,"kobe"}
    # s3 = s1.symmetric_difference(s2)
    s3 = s1 ^ s2
    print(s3)

    (5) xx.update 将得到的集合更新到s1

    s1.intersection_update(s2)
    print(s1)

    (6)isdisjoint 无交集返回True

    s1 = {11,22,33,"hechouzi"}
    s2 = {44,55}
    v = s1.isdisjoint(s2)

    (7)issubset  s2是s1的子集返回True

    s1 = {11,22,33,"hechouzi"}
    s2 = {11,22}
    v = s2.issubset(s1)
    print(v)

    (8)issuperset  s1是s2的父集返回True

    s1 = {11,22,33,"hechouzi"}
    s2 = {11,22}
    v = s1.issuperset(s2)
    print(v)

    (9) update 更新多个值

    s1 = {11,"hechouzi",(11,22,33)}
    s1.update((22,33))
    print(s1)

    二、字符串拼接

    1.%

    (1)%s 字符串类型,%d整型数字,%.2f 浮点数,小数点后2位默认6位,% .2f%%,百分比

    s = "I am %s,I am %d, percent %.2f, %.2f%%"%("hechouzi",25,42.8888,24.88888)
    print(s

    (2)字典

    s = "I am %(name)s,I am %(age)d"%{"name":"hechouzi","age":25}
    print(s)

    2.format

      *列表  **字典

      :b 二进制  :o 八进制  :d  整型  :x  十六进制小写  :X  十六进制大写

    s = "i am {},age{},{}".format("bigmouse",25,"dazui")
    print(s)
    s = "i am {},age{},{}".format(*["bigmouse",25,"dazui"])
    print(s)
    s = "i am {0},age{1},{1}".format("bigmouse",25,"dazui")
    print(s)
    s = "i am {2},age{1},{0}".format(*["bigmouse",25,"dazui"])
    print(s)
    s = "i am {name},age{age},{name}".format(name="bigmouth",age=25)
    print(s)
    s = "i am {name},age{age},{name}".format(**{"name":"bigmouth","age":25})
    print(s)
    s = "i am {0[0]},age{0[1]},{1[2]}".format([1,2,3],[11,22,33])
    print(s)
    s = "i am {:s},age {:d},length {:.3f}".format("dazui",24,2.1111)
    print(s)
    s = "i am {name:s},age {age:d},{length:.3f}".format(name="dazui",age=24,length=2.1111)
    print(s)
    s = "i am {name:s},age {age:d},{length:.3f}".format(**{"name":"dazui","age":24,"length":2.1111})
    print(s)
    s1 = "num1:{:b} {:o} {:d} {:x} {:X} {:.3%}".format(24,24,24,24,24,24.888888,)
    print(s1)

     

     

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  • 原文地址:https://www.cnblogs.com/hechengwei/p/8933954.html
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