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)