day7 集合

day7 集合
集合：可变的数据类型，里面的元素必须是不可变的数据类型
无序的，不重复
{}
set1 = set({1,2,3})
set2={1,2,3,[2,3],{'name':'alex'}}#集合里面的元素必须是不可变的数据类型
print(set1)
print(set2)
set1 = {'alex','wusir','ritian','egon','barry'}
#add
set1.add('女神')
print(set1)
set1.update('abc')
print(set1)
#删除
set1.pop()#随机删除
print(set1.pop()) #有返回值
print(set1)

set1.remove('alex') #按元素删除
print(set1)

#清空集合 空集合：set()
set1.clear()
print(set1)

#删除整个集合
del set1
print(set1)

#交集
set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
set3 = set1 & set2 #{4,5}
print(set1.intersection(set2)) #{4,5}
print(set3)
#并集
set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 | set2)
print(set2.union(set1))

#反交集
set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 ^ set2) # {1, 2, 3, 6, 7, 8}
print(set1.symmetric_difference(set2)) # {1, 2, 3, 6, 7, 8}

#差集
set1 = {1,2,3,4,5}
set2 = {4,5,6,7,8}
print(set1 - set2) # {1, 2, 3}
#set1独有的
print(set1.difference(set2)) # {1, 2, 3}

#子集
set1 = {1,2,3,}
set2 = {1,2,3,4,5,6}
print(set1 < set2)
print(set1.issubset(set2)) # 这两个相同，都是说明set1是set2子集。

#超级
print(set2 > set1)
print(set2.issuperset(set1)) # 这两个相同，都是说明set2是set1超集。

#面试题：列表去重
li=[1,2,33,33,2,1,4,5,6,6]
set1 = set(li)
print(set1)
li = list(set1)
print(li)

# frozenset不可变集合，让集合变得不可变
s = frozenset('barry')
print(s,type(s))
for i in s:
print(i)

import copy
l1 = [1,2,[4,5,6],3]
l2 = copy.deepcopy(l1)
print(l1,id(l1))
print(l2,id(l2))
l1[2].append('a')
print(l1,l2)

l1 = [1,[1],2,3,4]
l2 = l1[:]
l1[1].append('a')
l2 的结果是什么?

print(l1,id(l1))
print(l2,id(l2))
print(l1[1] is l2[1])

li = ['alex','taibai','wusir','egon']
for i in li:
print(li.index(i),i)

for index,i in enumerate(li,1):
print(index,i)

#循环中不能删除列表中元素，删除后索引后变
lis = [11,22,33,44,55]
# for i in range(len(lis)):
# print(i)
# del lis[i]
# print(lis)

基础数据类型汇总
str
# s = ''
# print(s.isspace())
int
'''
list:
'''
lis = [11,22,33,44,55]
for i in range(len(lis)):
print(i) # i = 0 i = 1 i = 2
del lis[i]
print(lis) # [11,22,33,44,55] [22, 44, 55] [22, 44]

#第一种
lis = lis[::2]
print(lis)

#第二种
l1 = []
for i in lis:
if lis.index(i) % 2 == 0:
l1.append(i)
lis = l1
print(lis)

lis = [11,22,33,44,55]
# for i in range(len(lis)-1,-1,-1):
# if i % 2 == 1:
# print(i)
# del lis[i]
# print(lis)
# print(lis)

dic = dict.fromkeys([1,2,3],'春哥')
print(dic)
dic = dict.fromkeys([1,2,3],[])
print(dic) # {1: [], 2: [], 3: []}
dic[1].append('袁姐')
print(dic)
dic[2].extend('二哥')
print(dic)

l1 = []
l2 = l1
l3 = l1
l3.append('a')
print(l1,l2,l3)

dic = {'k1':'v1','k2':'v2','a3':'v3'}
dic1 = {}

for i in dic:
if 'k' not in i:
dic1.setdefault(i,dic[i])
dic = dic1
print(dic)
l = []
for i in dic:
if 'k' in i:
l.append(i)
for i in l:
del dic[i]
print(dic)

转化成bool值
0 '' [] () {} set()

#元祖 如果元祖里面只有一个元素且不加,那此元素是什么类型，就是什么类型。
tu1 = (1)
tu2 = (1,)
print(tu1,type(tu1))
print(tu2,type(tu2))
tu1 = ([1])
tu2 = ([1],)
print(tu1,type(tu1))
print(tu2,type(tu2))
dic = dict.fromkeys([1,2,3,],3)
dic[1] = 4