Python学习笔记_day2

Posted 2020-10-09

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一、列表、元组

 1 names=["A","B","C","D"]
 2 print(names)
 3 print(names[0],names[2])
 4 print(names[1:3]) # 包括起始位置，不包括结束位置，顾头不顾尾。这个动作叫切片。
 5 print(names[-1])
 6 print(names[-1:-3]) # 切片从左到右
 7 print(names[-2:]) # 取到最后
 8 print(names[:3]) #从0取可以不写
 9 
10 names.append("E") #追加
11 print(names)
12 
13 names.insert(1,"F") #插入，1表示插入的位置 只能一个一个来，不能批量插入
14 print(names)
15 names.insert(3,"G")
16 print(names)
17 
18 names[2]="H" # 改
19 print(names)
20 
21 #delete
22 ‘‘‘names.remove("F")
23 print(names)‘‘‘
24 ‘‘‘del names[1]
25 print(names)‘‘‘
26 ‘‘‘names.pop(1) # 不输入下标删掉最后一个‘‘‘
27 print(names)
28 print(names.index("H"))
29 print(names[names.index("H")])
30 
31 names.append("A") # 可以重名
32 print(names.count("A"))
33 
34 ‘‘‘names.clear() # 清空
35 print(names)‘‘‘
36 
37 names.reverse()
38 print(names) #反转
39 
40 names.sort() #排序：#!>1>C>c 按ASCII码排序来的
41 print(names)
42 
43 names2=[1,2,3,4]
44 names.extend(names2) #并过来
45 print(names,names2)
46 del names2 #删除列表names2,print(names2)报错
47 print(names)
48 
49 names3=names.copy() #复制
50 print(names3)
51 
52 names[2]="三"
53 print(names)
54 print(names3)

names_list

 1 import copy
 2 
 3 names=["A","B","C",["E","F"],"D"]
 4 print(names)
 5 
 6 names2=copy.deepcopy(names) #copy.copy(names)和浅copy一样，深copy用处不大，知道就行
 7 print(names,names2,sep="\n")
 8 print(id(names),id(names2),sep="\n")
 9 
10 
11 names[3][0]="MM"
12 print(names,names2,sep="\n")

names_copy

 1 names=["A","B","C",["E","F"],"D"]
 2 print(names)
 3 
 4 names2=names.copy()  #names2=name还跟简单的str和数字不同，names2跟着names变
 5 print(names2)
 6 
 7 names[2]="三"
 8 print(names,names2,sep="\n")
 9 
10 names[3][0]="MM"
11 print(names,names2,sep="\n") #只copy第一层 ，改names2也一样
12 
13 names2[3][0]="GG"
14 print(names,names2,sep="\n")

sublist_names

 1 names=["A","B","C",["M","G"],"D","E"]
 2 
 3 for i in names:
 4     print(i)
 5 
 6 #切片
 7 #range(1,10,2)
 8 print(names[0:-1:2])
 9 print(names[::2])
10 print(names[:])

loop_sec_names

test.py:1、sys模块是Python解释器自带的用C语言写的，所以找不到。2、浅copy是引用列表。

 1 import copy
 2 person=["name",["salary",100]]
 3 
 4 ‘‘‘p1=copy.copy(person)
 5 p2=person[:]
 6 p3=list(person)
 7 print(p1,p2,p3,sep="\n")‘‘‘#三种浅copy方法
 8 
 9 p1=person[:]
10 p2=person[:]
11 
12 p1[0]="alex"
13 p2[0]="fengjie"
14 
15 p1[1][1]=50 #浅copy可以用来创建联合账号，共同存款的变化，但实际上不会这样用。
16 
17 print(p1)
18 print(p2)

test.py

元组不能更改，可理解为只读列表。两种方法：count、index

1 names=(("alex","jack"),(1,2),(8,9),(1,2),[6,7])
2 print(names.index((8,9))) #查询位置
3 print(names.count((1,2))) #出现次数

tuple

程序：购物车程序

需求:

启动程序后，让用户输入工资，然后打印商品列表
允许用户根据商品编号购买商品
用户选择商品后，检测余额是否够，够就直接扣款，不够就提醒

可随时退出，退出时，打印已购买商品和余额

 1 ‘‘‘shoplist=[[1,"Iphone",5800],[2,"Macbook",12000],[3,"Surfacelaptop",8888],[4,"Bike",800],[5,"Coffe",30]]
 2 salary=int(input("Enter integer salary of you:"))
 3 
 4 for i in shoplist:
 5     print(i)
 6 buy=input("Choose something you like and enter the serial number:")
 7 if buy==1:
 8     if salary>shoplist[0][3]:
 9         salary=salary-shoplist[0][3]
10         print("You have chosen the",shoplist[0][2])
11     else:
12         print("Your balance is not enough")
13 elif buy==2:
14     if salary>shoplist[1][3]:
15         salary=salary-shoplist[1][3]
16         print("You have chosen the",shoplist[1][3])
17     else:
18         print("Your balance is not enough")‘‘‘
19 #以上为自己编写的错误的思路
20 
21 product_list=[("Iphone",5800),
22               ("Mac Pro",9800),
23               ("Bike",800),
24               ("Watch",10600),
25               ("Coffee",31),
26               ("Alex Python",120)]
27 shopping_list=[]
28 while True:
29     salary=input("Input your salary:")
30     if salary.isdigit(): #判断是不是数字
31         salary=int(salary)
32         while True:
33             for index,item in enumerate(product_list): #enumerate把列表下标直接取出来
34                 #print(product_list.index(item),item)
35                 print(index+1,".",item,sep="")
36             user_choice=input(‘‘‘Choose something you like and enter the serial number (You can press "q "to quit)>>>:‘‘‘)
37             if user_choice.isdigit():
38                 user_choice=int(user_choice)
39                 if user_choice<=len(product_list) and user_choice>=1:
40                     p_item=product_list[user_choice-1]
41                     if p_item[1]<=salary:#买得起
42                         shopping_list.append(p_item)
43                         salary -=p_item[1]
44                         print("Added %s into shopping cart,your current balance is \033[31;1m%s\033[0m"%(p_item,salary)) #\033[31;1m...\033[0m 加颜色
45                     else:
46                         print("\033[31;1m你的余额只剩 %s 啦，还买个毛线!\033[0m"%salary)
47                 else:
48                     print("product code [%s] is not exist!"%user_choice)
49             elif user_choice=="q":
50                 print("------shopping list------")
51                 for p in shopping_list:
52                     print(p)
53                 print("Your current balane:",salary,"\nThank for your shopping and looking forward to your next visit!")
54                 exit()
55             else:
56                 print("Invalid option")
57     else:
58         print("Please enter an integer")

shoplist_

 1 product_list=[["Iphone",5800],["MacBook",8000],["Surfacelaptop",9999],["Iwatch",10000],["ThinkPad",12000]]
 2 shoplist=[]
 3 while True:
 4     salary = input("Enter your salary:")
 5     if salary.isdigit():
 6         salary=int(salary)
 7         while True:
 8             for item in product_list:
 9                 print(product_list.index(item)+1,".",item,sep="")
10             users_choice=input("Choose something you like\nEnter the sequence number to buy"
11                                   "(You can press the ‘q‘ to quit) --->:")
12             if users_choice.isdigit():
13                 users_choice = int(users_choice)
14                 if users_choice<=len(product_list) and users_choice>=1:
15                     if product_list[users_choice-1][1]<=salary:
16                         shoplist.append(product_list[users_choice-1])
17                         salary=salary-product_list[users_choice-1][1]
18                         print("Your current balance:",salary)
19                     else:
20                         print("你的钱只剩%s了，还买个毛线！"%salary)
21                         exit()
22                 else:
23                     print("Invalid option")
24             elif users_choice == "q":
25                 print("------shoplist------")
26                 for i in shoplist:
27                     print(i)
28                 print("Your curren balance:%s"%salary)
29                 print("Looking forward your next shopping!")
30                 exit()
31             else:
32                 print("Invalid option")
33     else:
34         print("Please enter an integer!")

shoplist_by_self

二、字符串操作

特性：不可修改　

 1 name="my\tname is {name} and i am {year} years old"
 2 print(name.capitalize())#首字母大写
 3 print(name.count("a"))#统计字母出现次数
 4 print(name.center(50,"-")) #居中
 5 print(name.endswith("ang")) #判断字符串是不是以..结尾
 6 print(name.expandtabs(tabsize=30)) #\t 加空格
 7 print(name[name.find("name"):]) #find找字符串位置，字符串也可以切片，用法与列表一样
 8 print(name.format(name="jyh",year=24))
 9 print(name.format_map({"name":"jyh","year":24})) #字典
10 print("ab23".isalnum()) #阿拉伯的数字和字符
11 print("ac".isalpha()) #纯英文字符
12 print("1A".isdecimal()) #判断十进制，没什么用
13 print("1A".isdigit()) #判断整数
14 print("A1".isidentifier())#判断是不是一个合法的标识符
15 print("a1".islower())#判断小写
16 print("1/3".isnumeric())#判断整数，没什么用
17 print(" ".isspace())#判断空格
18 print(" My Name Is ".istitle())#判断每个首字母是否大写
19 print(" My Name Is ".isprintable())#判断是否可以打印，用的很少 tty file,drive file
20 print(" My Name Is ".isupper())#判断大写
21 print("+".join(["1","2","3"])) #连接字符串，经常用
22 print(name.ljust(50,"*")) #长度50，不够在后面用*补
23 print(name.rjust(50,"-")) #长度50，不够在前面用-补
24 print("Alex".lower()) #大写变小写
25 print("Alex".upper()) #小写变大写
26 print("\n    Alex".lstrip()) #从左去掉空格后回车,rstrip同理，strip用得最多
27 
28 p=str.maketrans("abcdef",‘123456‘) #类似数字对应，必须一样多
29 print("alex li".translate(p))  #用的不多
30 
31 print("alex li".replace("l","L",1)) #替换
32 print("alex lil".rfind("l")) #从左往右，找到最后面值的下标
33 print("alex lil".split("l")) #按分隔符"l"将字符串分成列表
34 print("1+2+3+4".split("+")) #按分隔符"+"将字符串分成列表
35 print("1+2\n+3+4".splitlines()) #按换行符（识别不同系统的换行符）将字符串分成列表
36 print("Alex Li".swapcase()) #大小写互换
37 print("AleX Li".title()) #首字母变大写
38 print("AleX Li".zfill(50)) #没什么用

str

三、字典操作

字典一种key - value（键-值）的数据类型，使用就像我们上学用的字典，通过笔划、字母来查对应页的详细内容。

字典的特性：

dict是无序的

key必须是唯一的,so 天生去重

 1 #key-value 键-值
 2 info = {
 3     ‘stu1101‘: "A",
 4     ‘stu1102‘: "B",
 5     ‘stu1103‘: "C",
 6 }
 7 
 8 print(info)  #字典是无序的
 9 print(info["stu1101"]) #取值,查找
10 info["stu1101"]="D"  #改
11 info["stu1104"]="E" #创建
12 #del info["stu1101"]
13 #info.pop("stu1101")
14 #info.popitem() #随机删，别用，无意义
15 print(info)
16 
17 print(info["stu1101"]) #查找,没有的话出错
18 print(info.get("stu1105"))#查找,没有的话打印None
19 print("stu1107" in info) #查找,没有的话打印False #info.has_key("1107") in python2.x
20 
21 b={"stu1101":"Alex",1:3,2:5}
22 info.update(b)     # 有交叉的key覆盖，没有的话创建
23 print(info)
24 
25 print(info.items()) #把字典转成列表
26 
27 c=dict.fromkeys([6,7,8],[1,{"name":"alex"},444])  #初始化一个新的字典
28 print(c)
29 c[7][1]["name"]="Jack Chen"
30 print(c)    # 三个Key共享一个内存地址，也就是都会变成"Jack Chen"
31 
32 for i in info:
33     print(i,info[i])
34 
35 for k,v in info.items():
36     print(k,v)             #有一个将字典转化成列表的过程，速度慢

dictionary_

 1 av_catalog = {
 2     "A":{
 3         "A1": ["A11","A12"],
 4         "A2": ["A21","A22"],
 5         "A3": ["A31","A32"],
 6         "A4":["A41","A42"]
 7     },
 8     "B":{
 9         "B1":["B11","B12"]
10     },
11     "C":{
12         "C1":["C11","C12"]
13     }
14 }
15 
16 av_catalog["C"]["C1"][1]="C13"
17 print(av_catalog)
18 av_catalog.setdefault("C",{"C11":[1,2]})
19 print(av_catalog)
20 av_catalog.setdefault("D",{"C11":[1,2]}) #先到字典去key，取到返回，取不到，重新加一个
21 print(av_catalog)

dictionary2

程序练习

程序: 三级菜单

要求:

打印省、市、县三级菜单
可返回上一级

可随时退出程序

 1 data={
 2     ‘北京‘:{
 3         "昌平":{
 4             "沙河":["oldboy","test"],
 5             "天通苑":["链家地产","我爱我家"],
 6         },
 7         "朝阳":{
 8             "望京":{"奔驰","陌陌"},
 9             "国贸":{"CICC","HP"},
10             "东直门":{"Advent","飞信"},
11         },
12         "海淀":{},
13     },
14     ‘山东‘:{
15         "德州":{},
16         "青岛":{},
17         "济南":{},
18     },
19     ‘广东‘:{
20         "东莞":{},
21         "常熟":{},
22         "佛山":{},
23     },
24 }
25 exit_flag=False
26 while not exit_flag:
27     for i in data:
28         print(i)
29     choice=input("选择进入1>>>：")
30     if choice in data:
31         while not exit_flag:
32             for i2 in data[choice]:
33                 print("\t",i2)  #\t为了区分级别加空格
34             choice2 = input("选择进入2>>>：")
35             if choice2 in data[choice]:
36                 while not exit_flag:
37                     for i3 in data[choice][choice2]:
38                         print("\t\t", i3)
39                     choice3 = input("选择进入3>>>：")
40                     if choice3 in data[choice][choice2]:
41                         for i4 in data[choice][choice2][choice3]:
42                             print("\t\t\t",i4)
43                         choice4 = input("最后一层，按b返回>>")
44                         if choice4=="b":
45                             pass #占位符，否则报错
46                         elif choice4=="q":
47                             exit_flag=True
48                     if choice3 == "b":
49                         break
50                     elif choice3 == "q":
51                         exit_flag = True
52             if choice2 == "b":
53                 break
54             elif choice2 == "q":
55                 exit_flag = True
56     elif choice == "q":
57         exit_flag = True

three_level_menu

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Python学习笔记_Day2_数据类型及数据结构（列表和元组）

Python学习笔记_day2

一、 列表、元组

二、字符串操作

三、字典操作

一、列表、元组