Day3笔记

json操作：

#json就是一个字符串
d = {
        "error_code": 0,
        "stu_info": [
                {
                        "id": 314,
                        "name": "矿泉水",
                        "sex": "男",
                        "age": 18,
                        "addr": "北京市昌平区",
                        "grade": "摩羯座",
                        "phone": "18317155663",
                        "gold": 100
                },
                {
                        "id": 315,
                        "name": "矿泉水",
                        "sex": "女",
                        "age": 27,
                        "addr": "上海",
                        "grade": "摩羯座",
                        "phone": "18317155664",
                        "gold": 100
                }
        ]
}

import json
with open('abc.txt','w',encoding= 'utf-8') as fw:

    json.dump(d,fw,indent=4,ensure_ascii=False)
    s = json.dumps(d,ensure_ascii=False,indent=4) #把字典转成json，字符串
    fw.write(s)
    #ensure_ascii = False去中文
    #indent=4美化文件



with open('abc.txt',encoding= 'utf-8') as fr:
    result = fr.read()
    print('result,刚从文件读出来',type(result))
    dic = json.loads(result)
    print('dic,转换完了之后的',dic,type(dic))
#json转换成字典
    result = json.load(fr)
    print('result',type(result))

集合：

#集合天生可以去重set
l = [1,2,3,4,1,2,3,]
print(set(l))#集合是无序的

s2 = {1, 2, 3, 4}

s = set()#空集合
s.add(1)#添加元素
s.remove(1)#删除元素

#交集，并集，差集，对称差集
xn = ['1','2','3']
zdh = ['2','3','4']
xn_set = set(xn)
zdh_set = set(zdh)
print((xn_set.intersection(zdh_set))) # 取交集
print(xn_set & zdh_set)#取交集

#并集,把两个几个加一起去重
print(xn_set.union(zdh_set))
print(xn_set |zdh_set)

#差集,在a里面有的，在b里面没有的
print(xn_set.difference(zdh_set))
print(xn_set - zdh_set)

#对称差集,把两个集合里面都有的删掉
print(xn_set.symmetric_difference(zdh_set))
print(xn_set ^ zdh_set)

切片：

l = ['xiaoming', 'xiaohei', 'xiaobai', 'jaojun','小黑']
print(l[1:2])# 顾头不顾尾

print(l[0:6:3])# 2是隔一个取一个,负数是从右往左

#非空即真，非0即真
#列表生成式
for i in range(1,100):
    if i%2 == 0:
        l.append(i)
print(l)

result = [str(i).zfill(2) for i in  range(1,10)if i <10]#简化写作,后面可以加if条件
print(result)

result2 = []#同上一个意思
for i in range(1,10):
    j= str(i).zfill(2)
    result2.append(j)
print(result2)

result = [i+1 for i in range(1,10)]
result2=[]
for i in  range(1,10):
    result2.append(i+1)

print(result)

#三元表达式
id_card = '410881199211111111'
if id_card [-2]%2 == 0
    sex = 'nv'
else:
    sex = 'nan'

sex = '女' if int(id_card[-2] )%2 == 0 else '男'#三元表达式
print(sex)

li = [1,1,2,3,4,5,6,7,8,9]
li2 = [1,1,2,3,4,5,6,7,8,9]

import copy
#li2 = li[:] #深拷贝
#li2 = li    #浅拷贝
#li3 = copy.deepcopy(li)深拷贝

for i in li2:
    if i%2!=0:
        li.remove(i)
print(li)

#循环的时候不要删list里面的元素，会导致下标错乱
#两个list 可以避免此问题
#浅拷贝，深拷贝