Python学习之旅--第二周--元组字符串运算字典

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一、元组

另一种有序列表叫元组:tuple。tuple和list非常类似,但是tuple一旦初始化就不能修改,比如同样是列出同学的名字:

# Author:Tim Gu
tuple = ("Tim",Jack,mike)

  元组元素不可被修改,只读。不过有一种情况是内嵌列表的时候,列表内的元素可修改

# Author:Tim Gu
tuple = ("Tim",Jack,mike,[john,tom])
print(tuple)
tuple[3][1] = mary
print(tuple)
>>>
(Tim, Jack, mike, [john, tom])
(Tim, Jack, mike, [john, mary])


二、字符串

 输入时的空格处理: 

# Author:Tim Gu
username = input(user:)
if username.strip() == Tim: #去除输入时的空格
    print("welcome")

  输出:

user:          Tim
welcome

  字符串的拆分与合成:

names = Tim,jack,rain
name2 = names.split(",") #拆分
print(name2)
print(",".join(name2))  #组合
>>>
[Tim, jack, rain]
Tim,jack,rain

  判断字符串有没有空格

# Author:Tim Gu
name = Tim Gu
if ‘‘ in name:
    print(‘‘ in name)
>>>True

  字符串的格式化:format()

msg = "Hello, {name}, it‘s been a long {age} since time sopke..."
msg2 = msg.format(name=Tim,age=30)
print(msg2)
>>>
Hello, Tim, its been a long 30 since time sopke...

  

msg2 = "hahaha{0}, ddd{1}"
print(msg2.format("Tim",33))
>>>
hahahaTim, ddd33

  字符串切片

name = tim gu
print(name[1:3]) #打印序列字符
print(name.center(40,-)) #填满40个字符
print(name.find(m)) #搜索字符串中的字符,返回的第一个找到的值的索引,没有找到返回-1
print(name.find(b))
>>>
im
-----------------tim gu-----------------
2
-1

  判断输入是否数字

age = input(input you age:)
if age.isdigit(): #判断输入是否是数字
    age = int(age)
else:
    print(Invalid data type)
>>>
age = input(input you age:)
if age.isdigit(): #判断输入是否是数字
    age = int(age)
else:
    print(Invalid data type)

 判断输入是否包含特殊字符

 

name = Timsjl4
print(name.isalnum())
>>>
True

  字符特殊判断

name = Timsjl4
print(name.endswith(jl4)) #判断是否jl4结尾
print(name.startswith(Tim)) #判断是否Tim开头
print(name.upper()) #大写
print(name.lower()) #小写
>>>
True
True
TIMSJL4
timsjl4

 

三、运算:

  运算符:

  + 加

  - 减

  * 乘

  / 除

  ** 幂

  % 取摸--返回除法的余数

  // 取整数---返回商的整数

 

  比较运算:

  == 等于

  != 不等于

  >= 大于等于

  <=小于等于

  > 大于

  < 小于

 

  赋值运算:

  = 赋值

  +=加法赋值

  -=减法赋值

  *=乘法赋值

  /=除法赋值

  %=取模赋值

  **=幂赋值

  //取整除赋值

  

  逻辑运算:

  and 与---条件全为真返回True

  or 或 -----条件有一个为True,返回True

  not 布尔非

 

  分身运算:

  is 判断两个标识符是否引用自一个对象

  is not 判断两个标识符是不是发引用不同对象

 

  位运算:

  & 按位与运算符

  | 按位或运算符

  ^ 按位异或运算符

  ~ 按位取反运算符

  << 左移动运算符

  >> 右移动运算符

 

四、字典

  Python内置了字典:dict的支持,dict全称dictionary,在其他语言中也称为map,使用键-值(key-value)存储,具有极快的查找速度。

  字典中的key必须是唯一的。

id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}
print(id_db)

id_db[9527][name] = jeson #修改key
print(id_db[9527])

id_db[9531][wife_qq] = 59594399 #增加key和值
print(id_db[9531])

del id_db[9520][addr]  #删除key和值
print(id_db[9520])

id_db[9527].pop(addr) #删除key和值 等同于上面的del
print(id_db[9527])

输出:

{9520: {age: 23, name: Jack, addr: SuZhou}, 9531: {age: 30, name: Mike, addr: NanJing}, 9527: {age: 22, name: Tim, addr: ShangHai}}
{age: 22, name: jeson, addr: ShangHai}
{age: 30, name: Mike, wife_qq: 59594399, addr: NanJing}
{age: 23, name: Jack}
{age: 22, name: jeson}

  获取值:get()

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}
print(id_db)
v = id_db.get(9531) #一般使用get获取值
#v = id_db[9531]#不建议使用这个
print(v)

  输出:

{9520: {name: Jack, addr: SuZhou, age: 23}, 9531: {name: Mike, addr: NanJing, age: 30}, 9527: {name: Tim, addr: ShangHai, age: 22}}
{name: Mike, addr: NanJing, age: 30}

  

  update()

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}

dist2 = {
    9527:{
    name:zhangsan,
    age:10,
    addr:JiangXi
    }
}
print(id_db)
id_db.update(dist2)
print(id_db)

输出: 如果存在相同的key值,即覆盖。如不存在,则新建

{9520: {age: 23, addr: SuZhou, name: Jack}, 9531: {age: 30, addr: NanJing, name: Mike}, 9527: {age: 22, addr: ShangHai, name: Tim}}
{9520: {age: 23, addr: SuZhou, name: Jack}, 9531: {age: 30, addr: NanJing, name: Mike}, 9527: {age: 10, addr: JiangXi, name: zhangsan}}

  

  返回字典中的key或值,判断KEY是否存在:

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}

print(id_db)
print(id_db.values())
print(id_db.keys())
print(9527 in id_db)


  输出:

{9520: {addr: SuZhou, age: 23, name: Jack}, 9531: {addr: NanJing, age: 30, name: Mike}, 9527: {addr: ShangHai, age: 22, name: Tim}}
dict_values([{addr: SuZhou, age: 23, name: Jack}, {addr: NanJing, age: 30, name: Mike}, {addr: ShangHai, age: 22, name: Tim}])
dict_keys([9520, 9531, 9527])
True

 

  set.default():

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}

print(id_db.setdefault(9527)) #取一个key
print(id_db.setdefault(9333,dddd)) #如果不存在,新增一个默认的key和值


  输出:

{age: 22, addr: ShangHai, name: Tim}
dddd


 随机删除:popitem()

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}

print(id_db.popitem()) #随机删除一组数据
print(id_db)

  输出:

(9520, {name: Jack, addr: SuZhou, age: 23})
{9531: {name: Mike, addr: NanJing, age: 30}, 9527: {name: Tim, addr: ShangHai, age: 22}}

  

  字典转化为元组:items()

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}


print(id_db.items())
>>>
dict_items([(9520, {name: Jack, age: 23, addr: SuZhou}), (9531, {name: Mike, age: 30, addr: NanJing}), (9527, {name: Tim, age: 22, addr: ShangHai})])

  

  字典的循环:

# Author:Tim Gu
id_db = {
    9527:{
        name:Tim,
        age:22,
        addr:ShangHai
    },
    9520:{
        name:Jack,
        age:23,
        addr:SuZhou
    },
    9531:{
        name:Mike,
        age:30,
        addr:NanJing
    }
}

for key in id_db:
    print(key,id_db[key])

  输出:

9520 {age: 23, name: Jack, addr: SuZhou}
9531 {age: 30, name: Mike, addr: NanJing}
9527 {age: 22, name: Tim, addr: ShangHai}

 

五、集合 set

set和dict类似,也是一组key的集合,但不存储value。由于key不能重复,所以,在set中,没有重复的key。

  创建一个set

# Author:Tim Gu

s = set({1,3,4,5})
s2 = {1,2,3,4}
print(type(s))
print(s)
print(type(s2))
print(s2)
>>>
<class set>
{1, 3, 4, 5}
<class set>
{1, 2, 3, 4}

 s2其实是调用了set()的构造方法

 列表转化集合:

li = [11,22,11,22]
s1 = set(li)
print(s1)

  输出:

{11, 22}

  注意:集合是没有重复值的

   集合添加元素:

se = {1,2,5,6,4}
se.add(3)
print(se)
>>>
{1, 2, 3, 4, 5, 6}

  集合删除元素:

se = {1,2,5,6,4}
se.remove(5) #删除,如果5不存在,报错
se.discard(2)#删除,如果2不存在,不报错
print(se) >>> {1, 4, 6}

  集合是无序的无重复的元素的集合,所以两个set可以做交集、并集等操作:

se1 = {1,2,5,6,4}
se2 = {5,6,8,3,44}

print(se1&se2)
print(se1|se2)
>>>
{5, 6}
{1, 2, 3, 4, 5, 6, 8, 44}

 

  差集:  

s1 = {11,22,33}
s2 = {22,33,44}
s4 = {33,44,55}
s3 = s1.difference(s2)
print(s3)  #s1中存在,s2中不存在

s3 = s1.symmetric_difference(s2) #d对称差集
print(s3)

s1.difference_update(s2) #将s1更新为s1和s2的差集
print(s1)

  输出:

{11}
{11, 44}
{11}

 

s1 = {11,22,33}
s2 = {22,33,44}


s1.symmetric_difference_update(s2) #将s1更新为s1和s2的对称差集
print(s1)
>>>
{11, 44}

  

  pop移除:

s1 = {11,22,33}
ret = s1.pop() #因集合是无序的,pop()会随机移除元素,将移除的元素赋给ret
print(s1)
print(ret)
>>> {11, 22}
33

 
  并集:

s1 = {11,22,33}
s2 = {22,33,44}
s3 = s1.union(s2)
print(s3)
>>>
{33, 22, 11, 44}

  update()

s1 = {11,22,33}
li = [11,22,3,11,2]
s1.update(li)
print(s1)

s = tim
s1.update(s)
print(s1)
>>>
{3, 33, 2, 11, 22}
{33, 2, 3, t, i, 11, m, 22}

 

 

 

   第二周练习:完美购物车

要求:

购物车:
用户启动程序后打印商品列表
允许用户选择购买商品
允许用户不断地购买各种商品
购买时检测 余额是否足够,如果足够,直接扣款 否则打印余额不足
允许用户主动退出程序,退出时打印已购商品列表

# Author:Tim Gu

for i in range(3):
    salary = input(Input your salary:)
    if salary.isdigit():
        salary = int(salary)
        break
    else:
        print(Invaild data type...)
        if i == 2:
            print(Wrong!)
        continue

welcome_msg = Welcome to Tim Shopping mall.center(50, -)
print(welcome_msg)

exit_flag = False
product_list = [
    (Iphone,5888),
    (Mac Air,8000),
    (mac pro,9000),
    (xiaomi 2,19.2),
    (Coffer,30),
    (Tesla,820000),
    (Bike,700),
    (Cloth,200)
]

shop_car = []
while exit_flag != True:
    print(product list.center(50,-))
    for item in enumerate(product_list):#枚举元组
        index = item[0]
        p_name = item[1][0]
        p_price = item[1][1]
        print(index,p_name,p_price)
    user_choice = input([q=quit,c=check]What do you watn to buy?:)
    if user_choice.isdigit():#肯定是选择商品
        user_choice = int(user_choice)
        if user_choice < len(product_list):
            p_item = product_list[user_choice]
            if p_item[1] <= salary: #资金够买
                shop_car.append(p_item)
                salary -= p_item[1]
                print(Added [%s] into shop car,you current balance is \033[31;1m[%s]\033[0m%(
                    p_item[0],salary))
            else:
                print("Your balance is [%s],cannot afford this..."%salary)
    elif user_choice == q or user_choice == quit:
        print("purchased products as below".center(40,*))
        for item in shop_car:
            print(item)
        print("END".center(40,*))
        print("Your balance is [%s] last"%salary)
        exit_flag = True
    elif user_choice == c or user_choice == check:
        print("purchased products as below".center(40, *))
        for item in shop_car:
            print(item)
        print("END".center(40, *))
        print("Your balance is \033[41;1m[%s] last\033[0m" % salary)

 

  作业需求:

  

作业需求: 1.优化购物程序,购买时允许用户选择购买多少件

2.允许多用户登陆,下一次登录后,继续按上次的余额继续购买(可以充值)

3.允许多户查看之间的购买记录(记录要显示商品购买时间)

4.商品列表分级展示,比如 第一层菜单: 1.家电类 2.衣服 3.手机类 4.车类

随便选择一个,比如车类,进入第2层

1.BMW X3 300000

2.AUDI Q5 350000

3.pasate 333335

4 tesla model_3 430000

5.tesla model_s 8888888

5.显示已购买商品时,如果有重复的商品,不打印多行,而是在一行展示

id  p_name        num     total_price

1.  TeslaModelS    2        35000000

2.  coffee             4     10000

  














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