Python practices (four lists and tuples) and python practices

Python practices (four lists and tuples) and python practices

After a period of learning, I learned the list and tuples of python. This part is the basis of the subsequent functions, which is also the part of learning in any language. In fact, the process is very hard, but it is not a bad thing for me, I do not understand it anyway, it does not have any psychological burden. Think about what you have learned. The accumulation at this time is solid in every step.

 

List, tuples

A list is one of the most common data types in the future. You can use a list to conveniently store and modify data.

Definition list

Names = ["A", "B", "C", "D"]

Access the elements in the list by subscript. The subscript starts counting from 0.

Names [0] # The result is

Names [2] # The result is C.

Names [-1] # The result is D.

Names [-2] # The result is C.

 

Slice: Multiple Elements

>>> Names = ["Alex", "Tenglan", "Eric", "Rain", "Tom", "Amy"]
>>> Names [] # obtain numbers between subscript 1 and subscript 4, including 1, not 4
['Tenglanc', 'Eric ', 'rain']
>>> Names [1:-1] # obtain the values from subscript 1 to-1, excluding-1.
['Tenglanc', 'Eric ', 'rain', 'Tom']
>>> Names [0: 3]
['Alex ', 'tenglanc', 'Eric']
>>> Names [: 3] # If it is retrieved from the beginning, 0 can be ignored. The effect is the same as that in the previous sentence.
['Alex ', 'tenglanc', 'Eric']
>>> Names [3:] # If you want to get the last one, you must not write-1.
['Rain', 'Tom ', 'amy']
>>> Names [3:-1] # in this way,-1 will not be included
['Rain', 'Tom ']
>>> Names [0: 2] #2 is the representative. Every other element takes one
['Alex ', 'Eric', 'Tom ']
>>> Names [: 2] # the same effect as the previous sentence
['Alex ', 'Eric', 'Tom ']

 

Insert

Names = ["A", "B", "C", "D"]

Names. append ("E ")

Names. insert (1)

>>> A, E, B, C, D

 

Modify

Names = ["A", "B", "C", "D"]

Names [2] = "E"

>>> A, B, E, D

 

Delete

Names = ["A", "B", "C", "D"]

Method 1: names. remove ("")

Print (names)

The output values are B, C, and D.

Method 2: del names [0]

Print (names)

The output values are B, C, and D.

Names. pop (0)

Print (names)

The output value is B, C, D #. If pop () does not write a number, the last one is deleted by default.

 

Statistics

Names = ["A", "B", "C", "D"]

Print (nams. count (C ))

 

Clear

Names = ["A", "B", "C", "D"]

Names. clear ()

Print (names)

The list is cleared.

 

Reverse

Names = ["A", "B", "C", "D"]

Names. reverse ()

Pritnt (names)

>>> D, C, B,

 

Sort

>>> Names

['Alex ', 'amy', 'amy ', 'tenglanc', 'Tom', '1', '2', '3']

>>> Names. sort ()

>>> Names

['1', '2', '3', 'Alex ', 'amy', 'amy ', 'tenglanc', 'Tom']

 

Extension

>>> Names
['Alex ', 'tenglanc', 'rain', 'Tom', 'amy ']
>>> B = [1, 2, 3]
>>> Names. extend (B)
>>> Names
['Alex ', 'tenglanc', 'rain', 'Tom', 'amy ', 1, 2, 3]

 

Tuples

The number of tuples is similar to that of the list. It is also called the read-only list.

Syntax:

names = ( "A" , "B" , "C" )It only has two methods: count and index. Program exercises

Program: Shopping Cart program

Requirements:

Product_list = [('phone ', 5800 ),

('Mac Pro', 9800 ),

('Bike', 800 ),

('Watch ', 10600 ),

('Coffee ', 31)]

Shopping_list = []

Salary = input ("input your salary :")

If salary. isdigit ():

Salary = int (salary)

While True:

For index, item in enumerate (product_list ):

Print (index, item)

User_choice = input ("Please Select Product :")

If user_choice.isdigit ():

User_choice = int (user_choice)

If user_choice <len (product_list) and user_choice> = 0

P_item = product_list [user_choice]

If p_item [1] <= salary: # Buy

Shopping_list.apeend (p_item)

Salary-= p_item (1)

Print ("Added % s into shopping cart, your current balance is \ 033 [31; 1 m % s \ 033 [0 m" % (p_item, salary ))

Else:

Print ("\ 033 [41; 1 m your balance is only [% s], you cannot purchase \ 033 [0 m" % alary)

Elif user_choice = 'Q'

Ptint ("-------- shopping list ------------")

For p in shopping_list:

Print (p)

Print ("Your current balance:", salary)

Exit ()

Else

Print ("invalid option ")

 

Summary: The focus of this chapter is the list. No matter what language you want to learn, it is essential to read the list several times. We recommend that you read the list several times, rather slow down and lay a solid foundation.