基础数据类型汇总

'''
list:
'''
li = [11,22,33,44,55]
del li[1]
print(li)
for i in li:
    # print(i)
    # print(li.index(i))
    # print(li[li.index(i)])
    # del li[1]
    del li[li.index(i)] # 因为列表是可变的数据类型，第一次循环之后，索引对应的元素发生了变化，因此删不完。
print(li)  # 结果：[22, 44]




删除奇数位 方法1
li = [11,22,33,44,55]
print(li[0::2])
del li[0::2]
print(li)


删除奇数位 方法2
li = [11,22,33,44,55]
# i = 0
# print(len(li))
li1 = []
for i in range(len(li)):
    if i%2 ==0:
        # print(li[i])
        li1.append(li[i])
# print(li1)
s = len(li1)
# print(s)
for i in range(len(li1)):
    for b in li:
        if b==li1[i]:
            del li[li.index(b)]
print(li)


删除奇数位 方法3
li = [11,22,33,44,55]
li1 = []
for i in range(len(li)):
    if i%2 ==0:
        # print(li[i])
        li1.append(li[i])
# print(li1)
set1 = set(li)
set2 = set(li1)
print(set1.difference(set2))
print(set1.symmetric_difference(set2))


dic = {'k1':'v1','k2':'v2','a3':'v3'}
dic1 = {}
for i in dic:
    # print(i)
    if 'k' not in i:
        print(i)
        s = i
        # dic1.setdefault(i,dic[i])
        dic1.update(s=dic[i])  # 奇怪 ????
# print(dic1)
dic = dic1
print(dic)




dic = {'name': '太白', 'age': 18}
dic['name'] = 'barry'
dic['weight']=''
dic.setdefault('heigh','180cm') # 增加
print(dic)
dic.update(sex='男')  # 增加
print(dic)


转换成bool 是False的 有哪些？ 0 ''  []  ()  set()


元祖  如果元祖里面只有一个元素且不加‘,’逗号 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))
结果
1 <class 'int'>
(1,) <class 'tuple'>

tu1 = ([1])
tu2 = ([1],)
print(tu1,type(tu1))
print(tu2,type(tu2))
结果
[1] <class 'list'>
([1],) <class 'tuple'>

dic = dict.fromkeys([1,2,3,],3)
dic[1] = 4
print(dic)