Python笔记-字典的练习

chars = ['a','c','d','s','a','c','d','s','c']
char_count = {}
for char in chars:
    if char in char_count:
        char_count[char] += 1
    else:
        char_count[char] = 1

    #if char not in char_count:
        #char_count[char] = charss.count(char)

print(char_count)

"""*********************************************"""
#让用户输入姓名，判断是否存在，若不存在，则添加到列表里
persons = [
    {'name':'zhangsan','age':18,},
    {'name':'lisi','age':'20'},
    {'name':'wangwu','age':'19'},
    {'name':'tom','age':'21'},
]
x = input('请输入你的姓名:')
for person in persons:
    #if name in person:     #in运算符，如果直接用在字典里，是用来判断key是否存在
    if person['name'] == x:
        print('您输入的名字已存在')
        break
else:
    #print('您输入的名字不存在')
    #创建一个新的字典  new_person
    new_person = {'name':x}
    y = int(input('请输入您的年龄:'))
    new_person['age'] = y

    #把这个新的数据存储到person列表里
    persons.append(new_person)
    print('用户添加成功')

confusion = {}
confusion[1] = 1
confusion['1'] = 2
confusion[1] += 1

sum = 0
for k in confusion:
    sum += confusion[k]

print(sum)

###################################################
dict1 = {'A':'100','B':'200','C':'300'}
dict2 = {}
for k,v in dict1.items():
    dict2[v] = k
dict1 = dict2
# dict1 = {v:k for k,v in dict1.items()}      字典推导式
print(dict1)

结果

{'a': 2, 'c': 3, 'd': 2, 's': 2}
请输入你的姓名:curry
请输入您的年龄:30
用户添加成功
4
{'100': 'A', '200': 'B', '300': 'C'}

Process finished with exit code 0

#声明一个字典保存学生信息（姓名，年龄，成绩，电话，性别...）
Student = {'name':'curry','sex':'male','age':'30','tel':'123456789','score':'100'}

#声明一个列表，里面包含6个字典
student1 = [
    {'name':'curry','sex':'male','age':15,'tel':'13545678914','score':10},
    {'name':'tom','sex':'female','age':20,'tel':'16256852178','score':70},
    {'name':'jimmy','sex':'female','age':13,'tel':'16415667','score':50},
    {'name':'jerry','sex':'male','age':16,'tel':'193456642','score':80},
    {'name':'chirs','sex':'female','age':20,'tel':'158310567230','score':66},
    {'name':'culi','sex':'male','age':24,'tel':'13341902089','score':40},
]
#1.统计不及格的人数
count = 0
teenage_count = 0
for student in student1:
    if student['score'] < 60:
        count += 1
print('不及格的学生有%d个'%count)

#2.打印不及格的学生和对应的成绩
for student in student1:
    if student['score'] < 60:
        print('%s不及格，分数是%d'%(student['name'],student['score']))
        print(student)
    if student['age'] < 18:
        teenage_count += 1
    if student['tel'].endswith('9'):
   #if student['tel'][-1] == 9:
        print('%s的手机号以9结尾'%student['name'])
print('不及格的学生有%d个'%count)
print('未成年的学生有%s个'%teenage_count)

结果

不及格的学生有3个
curry不及格，分数是10
{'name': 'curry', 'sex': 'male', 'age': 15, 'tel': '13545678914', 'score': 10}
jimmy不及格，分数是50
{'name': 'jimmy', 'sex': 'female', 'age': 13, 'tel': '16415667', 'score': 50}
culi不及格，分数是40
{'name': 'culi', 'sex': 'male', 'age': 24, 'tel': '13341902089', 'score': 40}
culi的手机号以9结尾
不及格的学生有3个
未成年的学生有3个

Process finished with exit code 0

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