集合类型内置方法(set)
集合可以理解成一个集合体，学习Python的学生可以是一个集合体；学习Linux的学生可以是一个集合体。
pythoners = ['nash', 'langyigang', 'fujiancheng', 'jinyi']
linuxers = ['nash', 'yankeming', 'zhaoyanrun']
# 即报名pythoners又报名linux的学生
py_li_list = []
for stu in pythoners:
if stu in linuxers:
py_li_list.append(stu)
print(f"pythoners and linuxers: {py_li_list}")上述的列表方式求两个集合体的关系运算非常复杂，因此有了我们的集合数据类型。
1.用途：
用于关系运算的集合体，由于集合内的元素无序且集合元素不可重复，因此集合可以去重，但是去重后的集合会打乱原来元素的顺序。
2.定义：
{}内用逗号分隔开多个元素，每个元素必须是不可变类型。
s = {1, 2, 1, 'a'} # s = set({1,2,'a'})
print(f"s: {s}")s: {1, 2, 'a'}
s = {1, 2, 1, 'a', 'c'}
for i in s:
print(i)1 2 c a
s = set('hello')
print(f"s: {s}")s: {'e', 'o', 'h', 'l'}
3.常用操作+内置方法：
集合的相关方法
1.长度len
2.成员运算in和not in
3.|并集、union
4.&交集、intersection
5.-差集、difference
6.^对称差集、symmetric_difference
7.==
8.父集：>、>= 、issuperset
9.子集：<、<= 、issubset
10.add
11.remove
12.difference_update
13.discard
14.isdisjoint
1.长度len
# set之长度len
s = {1, 2, 'a'}
print(f"len(s): {len(s)}")len(s): 3
2.成员运算in和not in
# set之成员运算in和not in
s = {1, 2, 'a'}
print(f"1 in s: {1 in s}")1 in s: True
3.|并集
# str之|并集
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
print(f"pythoners|linuxers: {pythoners|linuxers}")
print(f"pythoners.union(linuxers): {pythoners.union(linuxers)}")\# union:联合的意思 pythoners|linuxers: {'nash', 'langyigang', 'jinyi', 'yankeming', 'fujiancheng', 'zhaoyanrun'} pythoners.union(linuxers): {'nash', 'langyigang', 'jinyi', 'yankeming', 'fujiancheng', 'zhaoyanrun'}
4.&交集
# str之&交集
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
print(f"pythoners&linuxers: {pythoners&linuxers}")
print(f"pythoners.intersection(linuxers): {pythoners.intersection(linuxers)}")\# intersection:交集 pythoners&linuxers: {'nash'} pythoners.intersection(linuxers): {'nash'}
5.-差集
# str之-差集
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
print(f"pythoners-linuxers: {pythoners-linuxers}")
print(f"pythoners.difference(linuxers): {pythoners.difference(linuxers)}")
\# difference:反向差集 pythoners-linuxers: {'langyigang', 'fujiancheng', 'jinyi'} pythoners.difference(linuxers): {'langyigang', 'fujiancheng', 'jinyi'}
6.^对称差集
# str之^对称差集
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
print(f"pythoners^linuxers: {pythoners^linuxers}")
print(
f"pythoners.symmetric_difference(linuxers): {pythoners.symmetric_difference(linuxers)}")\# symmetric_difference:对称差集 pythoners^linuxers: {'fujiancheng', 'yankeming', 'jinyi', 'zhaoyanrun', 'langyigang'} pythoners.symmetric_difference(linuxers): {'fujiancheng', 'yankeming', 'jinyi', 'zhaoyanrun', 'langyigang'}
7.==
# str之==
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
javers = {'nash', 'yankeming', 'zhaoyanrun'}
print(f"pythoners==linuxers: {pythoners==linuxers}")
print(f"javers==linuxers: {javers==linuxers}")pythoners==linuxers: False javers==linuxers: True
8.父集：>、>=
# str之父集：>、>=
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
javaers = {'nash', 'zhanyanrun'}
print(f"pythoners>linuxers: {pythoners>linuxers}")
print(f"pythoners>=linuxers: {pythoners>=linuxers}")
print(f"pythoners>=javaers: {pythoners>=javaers}")
print(f"pythoners.issuperset(javaers): {pythoners.issuperset(javaers)}")
\# issuperset:子集 pythoners>linuxers: False pythoners>=linuxers: False pythoners>=javaers: False pythoners.issuperset(javaers): False
9.子集：<、<=
# str之子集：<、<=
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
javaers = {'nash', 'zhanyanrun'}
print(f"pythoners<linuxers: {pythoners<linuxers}")
print(f"pythoners<=linuxers: {pythoners<=linuxers}")
print(f"javaers.issubset(javaers): {javaers.issubset(javaers)}")\# issuperset:子集 pythoners<linuxers: False pythoners<=linuxers: False javaers.issubset(javaers): True
10.add
# set之add()
s = {1, 2, 'a'}
s.add(3)
print(s){1, 2, 3, 'a'}
11.remove
# set之remove()
s = {1, 2, 'a'}
s.remove(1)
print(s){2, 'a'}
12.difference_update
# str之difference_update()
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyanrun', 'yankeming'}
pythoners.difference_update(linuxers)
print(f"pythoners.difference_update(linuxers): {pythoners}")pythoners.difference_update(linuxers): {'fujiancheng', 'langyigang', 'jinyi'}
13.discard
# set之discard()
s = {1, 2, 'a'}
# s.remove(3) # 报错
s.discard(3)
print(s){1, 2, 'a'}
14.isdisjoint
# set之isdisjoint()，集合没有共同的部分返回True，否则返回False
pythoners = {'nash', 'langyigang', 'fujiancheng', 'jinyi'}
linuxers = {'nash', 'zhaoyantun', 'yankeming'}
pythoners.isdisjoint(linuxers)
print(f"pythoners.isdisjoint(linuxers): {pythoners.isdisjoint(linuxers)}")pythoners.isdisjoint(linuxers): False
4.存一个值or多个值：
多个值，且值为不可变类型。
5.有序or无序：
无序
s = {1, 2, 'a'}
print(f'first:{id(s)}')
s.add(3)
print(f'second:{id(s)}')first:4480523848 second:4480523848
6.可变or不可变：
可变数据类型