标签：on() lov name sub print %s mat 不可 amp
可变不可变：
可变：列表
不可变：字符串，数字，元组
访问顺序：
1.直接访问：数字
2.顺序访问：字符串，列表，元组
3.映射：字典
存放元素个数：
容器类型：列表，元组，字典
原子：数字，字符串
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定义：由不同的元素组成的集合，集合是一种无序排列的可hash值，可以作为字典的key（只可存放不可变类型，即只能存放字符串，数字，元组）
定义集合：例：s = {1，2，3，4，5，6}
例：add() 添加 s = {1,2,3,4,5,6} s.add("3") print(s) 结果：{1, 2, 3, 4, 5, 6, ‘3‘} 例：clear()清空 例：copy()拷贝 例： pop()删除，随机删除 例： remov(),删除指定元素，元素不存在会报错 例：discard(),删除指定元素，元素不存在不会报错
集合的关系
例：intersection(),交集 ==& ps = ["aa","bb","cc","dd"] ls = ["bb","cc","ee","ff"] p_s = set(ps) l_s = set(ls) print(p_s.intersection(l_s)) === print(p_s&l_s) 结果：{‘bb‘, ‘cc‘} 例：union(),并集 ==| ps = ["aa","bb","cc","dd"] ls = ["bb","cc","ee","ff"] p_s = set(ps) l_s = set(ls) print(p_s.union(l_s)) ===print(p_s|l_s) 结果：{‘aa‘, ‘bb‘, ‘ee‘, ‘cc‘, ‘ff‘, ‘dd‘} 例：difference()，差集 ==- ps = ["aa","bb","cc","dd"] ls = ["bb","cc","ee","ff"] p_s = set(ps) l_s = set(ls) print(p_s-l_s) 结果：{‘aa‘, ‘dd‘} 例：symmetric_difference(),交叉补集 ==^ ps = ["aa","bb","cc","dd"] ls = ["bb","cc","ee","ff"] p_s = set(ps) l_s = set(ls) print(p_s.symmetric_difference(l_s)) 结果：{‘dd‘, ‘ff‘, ‘aa‘, ‘ee‘}
例：difference_update()，差集以后更改原数据 ps = ["aa","bb","cc","dd"] ls = ["bb","cc","ee","ff"] p_s = set(ps) l_s = set(ls) p_s.difference_update(l_s) print(p_s) 结果：{‘aa‘, ‘dd‘} 例：isdisjoint(),比较2个集合是否有交集，有交集返回False 例：issubset(),包含关系，s1是s2的子集返回True 例：issuperset(),包含关系，s1是s2的父集返回True === >=
1.format
例：传单个值
print("i am %s my" %‘hhh‘)
结果：i am hhh my
例：传多个值
print(‘i am %s i love %s‘ % ("dl","maod"))
结果：i am dl i love maod
例：
tpl = "percent %f "% 8.8888
print(tpl)
结果：percent 8.888800
tpl = "prcent %0.3f "% 8.8888 ==保留小数点后3位
print(tpl)
结果：prcent 8.889
print("root","x","0","2",sep=":")
结果：root:x:0:2
tpl = "i am %(name)s and age is %(age)d" % {"name": "dl","age": 18}
print(tpl)
结果：i am dl and age is 18
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标签：on() lov name sub print %s mat 不可 amp
原文地址：https://www.cnblogs.com/liuchunling/p/10871030.html
