Python Learning Notes (lists, tuples, shopping cart instances)

First, List

Lists and dictionaries are two of the most common data types

1. Requirements: How to store the class more than 80 people's name, how to achieve?

names = ["Zhangyang", "Guyun", "Xiangpeng", "Xuliangchen"]print (names[0],names[2]) #取出 Zhangyang xiangpengprint (names[ 2:4]) #切片, remove "Xiangpeng", "Xuliangchen" and output print (Names[0:4]) #切片, remove "Zhangyang", "Guyun", "Xiangpeng", "Xuliangchen"] Print (Names[-1]) #切片, negative numbers refer back to print (names[-2:]) #取最后2个值

Note: The front and back 0 can be omitted

2. Examples of various operations of the list

names = "Zhangyang Guyun xiangpeng xuliangchen" #以此列表为例

Increase:

Names.append ("Leihaidong") #在列表最后增加

Insert:

Names.insert (1, "Chenronghua") #位置1, insert Data Names.insert (3, "Xinzhiyu") #位置3, insert data

Modify:

NAMES[2] = "Xiedi" #下标位置2, replaced with "Xiedi"

Delete: (Three ways)

Names.remove ("Chenronghua") #删除列表中指定数据del names[1] #删除下标位置1的数据names. Pop () #不加下标, delete the last data, add subscript, and Del effect is the same

Copy:

(1)

names = ["Zhangyang", "Guyun", "Xiangpeng", "xuliangchen"]names2 = Names.copy () names[2] = "Peng" Print (names) print (Names2)

(2)

A.

names = ["Zhangyang", "Guyun", "Xiangpeng", ["Alex", "Jack"], "xuliangchen"]names2 = Names.copy () #浅copy, copy only the first layer names[2] = "To Peng" names[3][0] = "ALEX" Print (names) print (Names2)

View the output, Names2, Xiangpeng is not changed, the data in the sub-list is modified. Because the data in the child list is just a memory address, copy only the memory address

B. Shallow copy, The purpose of shallow copy: Create a federated account

Import copynames = ["Zhangyang", "Guyun", "Xiangpeng", ["Alex", "Jack"], "xuliangchen"]names2 = copy.copy (names) print ( Names) print (names2) names[2] = "to Peng" names[3][0] = "ALEX" Print (names) print (Names2)

(3) deep copy

Import copynames = ["Zhangyang", "Guyun", "Xiangpeng", ["Alex", "Jack"], "xuliangchen"]names2 = copy.deepcopy (names) Print (names) print (names2) names[2] = "to Peng" names[3][0] = "ALEX" Print (names) print (Names2)

At this point,names and Names2 will be two separate data.

List loop:

For i in Names:    print (i)

List slices:

Print (Names[0:-1:2]) print (Name[::2])

The above two commands have the same effect, and the data in the output list is spaced out. 0 and 1 in the list operation can be omitted.

Two, the meta-group

Tuples are actually similar to the list, but also to save a group of numbers, but once it is created, it can no longer be modified, so it is called a read-only list.

Grammar:

Names = (' Alex ', ' Jack ')

Tuples have only 2 methods, one is count, the other is index

Third, the procedure practice

Program: Shopping Cart Program

Demand:

1. After you start the program, let the user enter the payroll, and then print the list of items
2. Allow users to purchase items based on their product number
3. After the user selects the product, checks whether the balance is enough, enough on the direct debit, enough to remind
4. You can exit at any time to print the purchased goods and balances when exiting

The code is as follows:

Shopping_list = [] #已购买的商品列表, pre-defined empty list salary = input ("Please input your saraly:") # After starting the program, let the user enter payroll product_list = [(' Iphon E ', 5800), (' bike ', +), (' coffee ', +), (' Macbook Pro ', 12000), (' Alex Python ', Bayi), (' A ', ')]if Salary.isdig It (): salary = Int (salary) while True:for Index,item in Enumerate (product_list): #从商品列表中取数据和下标 # Print (Product_list.index (item), item) print (index,item) User_choice = input ("Select the item you want to buy?") >>>: ") If User_choice.isdigit (): #如果输入的是数字 user_choice = Int (user_choice) #转数据类型 if User_choice < Len (product_list) and User_choice >= 0: #如果输入的商品序列号在列表下标范围内, enter the shopping process P_item = Product_lis                    T[user_choice] If p_item[1] <= salary: #买得起 shopping_list.append (P_item) Salary-= p_item[1] Print ("Added%s into shopping cart,your current balance is \033[31;1m%s\033[  0m "% (p_item,salary)) Else:                  Print ("\033[41;1m your balance is left [%s], can't buy this item \033[0m"%salary) else:print ("Product Code             [%s] is not exist!!! "%user_choice) elif User_choice = = ' Q ': print ("---------shopping list---------") For P in Shopping_list:print (p) print ("Your Current balance:", salary) ex It () else:print ("Invalid option")

Python Learning Notes (lists, tuples, shopping cart instances)