数据类型之集合

集合（set）

集合的元素是无序的，不重复的
1.独有功能

1.增加元素
v = {1,"sundy","a","b"}
v.add("hh")
print(v)
v.add("hh")
print(v)
D:python3.6python3.6.exe D:/python_code/day01/day06.py
{1, 'sundy', 'hh', 'b', 'a'}

#2.删除元素
v = {1,"sundy","a","b"}
v.discard("a")
print(v)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
{1, 'sundy', 'b'}

#3.update批量添加
v = {1,"sundy","a","b"}
v.update({'ah','c','s'})
print(v)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
{'ah', 1, 'c', 's', 'a', 'sundy', 'b'}

#4.交集
v = {1,"sundy","a","b"}
result = v.intersection({1,"a"}) #可以是列表
print(result)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
{1, 'a'}

#5.并集
v = {1,"sundy","a","b"}
result = v.union({1,"a"}) #可以是列表
print(result)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
{1, 'a', 'sundy', 'b'}

#6.差值
v = {1,"sundy","a","b"}
result = v.difference({1,"a","d"})   #v中有，而{1,"a","d"}中没有的元素 #可以是列表
print(result)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
{'b', 'sundy'}

小结：

1.空集合：
v = set()
print(type(v))

D:python3.6python3.6.exe D:/python_code/day01/day06.py
<class 'set'>

#整型没有空
v=int() 值为0
D:python3.6python3.6.exe D:/python_code/day01/day06.py
<class 'set'>
0

#空字符串（str）
v = ""
v1 = str()
print(v,v1)

#空列表
v = []
v1 = list()
print(v,v1)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
[] []

#空元组
v = ()
v1 = tuple()
print(v,v1)

D:python3.6python3.6.exe D:/python_code/day01/day06.py
() ()

#空字典
v = {}
print(type(v))
D:python3.6python3.6.exe D:/python_code/day01/day06.py
<class 'dict'>