Format of <1> List

Sequences are the most basic data structure in Python.

- Format

#The type of variable A is a list.
namesList = ['xiaoWang','xiaoZhang','xiaoHua']
print(namesList[0])
print(namesList[1])
print(namesList[2])
# What's more powerful than C's arrays is that the elements in the list can be of different types.
testList = [1, 'a']

- visit

#!/usr/bin/python
 
list1 = ['physics', 'chemistry', 1997, 2000]
list2 = [1, 2, 3, 4, 5, 6, 7 ]
 
print "list1[0]: ", list1[0]
print "list2[1:5]: ", list2[1:5]

The output of the above example is as follows:

list1[0]: physics

list2[1:5]: [2, 3, 4, 5]

< 2 > Printed List

- Use the for loop

namesList = ['xiaoWang','xiaoZhang','xiaoHua']
    for name in namesList:
        print(name)

- Use the while loop

 namesList = ['xiaoWang','xiaoZhang','xiaoHua']

    length = len(namesList)

    i = 0

    while i<length:
        print(namesList[i])
        i+=1

List script operator < 3 >

The list pair + and * operators are similar to strings. + Number * is used for combination lists and * is used for repetition lists.

>>>L = ['Google', 'Runoob', 'Taobao']
>>> L[2]
'Taobao'
>>> L[-2]
'Runoob'
>>> L[1:]
['Runoob', 'Taobao']
>>>

Description:

Related operations of < 4 > List

Python contains the following functions:

Python includes the following methods:

- Add elements ("add" append, extend, insert)

• append
  append lets you add elements to a list

 #Define variable A with three elements by default
A = ['xiaoYu','xiaoHu','xiaoGuo']

print("----------")
for tempName in A:
    print(tempName)

#Prompt and add elements
temp = input('name:')
A.append(temp)

print("-----after add-----")
for tempName in A:
    print(tempName)

xiaoYu
xiaoHu
xiaoGuo
name:111
-----after add-----
xiaoYu
xiaoHu
xiaoGuo
111

• extend
  You can add elements from another collection to the list one by one through extension

a = [1, 2]
b = [3, 4]
a.append(b)
print a
a.extend(b)
print a

• insert
  insert(index, object) inserts the element object before the specified position index

a = [0, 1, 2]
a.insert(1, 3)
print a

- Modify elements ("change")

#Define variable A with three elements by default
A = ['xiao1','xiao2','xiao3']

print("----------")
for tempName in A:
    print(tempName)

#Modifying elements
A[1] = 'xiao4'

print("-----after modify-----")
for tempName in A:
    print(tempName)

xiao1
xiao2
xiao3
-----after modify-----
xiao1
xiao4
xiao3

- Find Elements ("Find" in, not in, index, count)

The so-called lookup is to see if the specified element exists.

in, not in
The common methods of searching in python are:

• in (exists), if it exists, then the result is true, otherwise it is false.
• not in, if not, then the result is true, otherwise false

#List to be found
nameList = ['xiao1','xiao2','xiao3']

#Get the name the user is looking for
findName = input('name:')

#Find out if it exists
if findName in nameList:
    print('same name')
else:
    print('not same')

name:222
not same

Explain:

• index, count
  index and count are used in the same way as in strings

a = ['a', 'b', 'c', 'a', 'b']
a.index('a', 1, 3) # Note that the left closed right open interval
Traceback (most recent call last):
File "", line 1, in
ValueError: 'a' is not in list

a.index('a', 1, 4)
3

a.count('b')
2

a.count('d')
0

- Delete elements ("Delete", del, pop, remove)

Analogy in real life, if a classmate transferred, then the name of the student after this article should be deleted; in the development of this function is often used to delete.

The common deletion methods of list elements are:

del: Delete by subscript
pop: Delete the last element
remove: Delete based on the value of the element
demo:(del)

movieName = ['Pirates of the Caribbean','Hacker empire','First Blood','Lord of the rings','The Hobbit','Fast & Furious']

print('------Before deleting------')
for tempName in movieName:
    print(tempName)

del movieName[2]

print('------After deletion------')
for tempName in movieName:
    print(tempName)

Result:

Before deletion
 Pirates of the Caribbean
 Hacker empire
 First Blood
 Lord of the rings
 The Hobbit
 Fast & Furious
 After deletion - ----------------------------------------------------------------------------------------------------------
Pirates of the Caribbean
 Hacker empire
 Lord of the rings
 The Hobbit
 Fast & Furious

demo:(pop)

    movieName = ['Pirates of the Caribbean','Hacker empire','First Blood','Lord of the rings','The Hobbit','Fast & Furious']

    print('------Before deleting------')
    for tempName in movieName:
        print(tempName)

    movieName.pop()

    print('------After deletion------')
    for tempName in movieName:
        print(tempName)

Result:

demo:(remove)

    movieName = ['Pirates of the Caribbean','Hacker empire','First Blood','Lord of the rings','The Hobbit','Fast & Furious']

    print('------Before deleting------')
    for tempName in movieName:
        print(tempName)

    movieName.remove('Lord of the rings')

    print('------After deletion------')
    for tempName in movieName:
        print(tempName)

Result:

- sort (reverse)

The sort method is to rearrange the list in a specific order. By default, the list is from small to large, and the parameter reverse=True can be changed to reverse order, from large to small.

The reverse method is to invert the list.

a = [1, 2, 3, 4]
print a
a.reverse()
print a
a.sort()
print a
a.sort(reverse=True)
print a

Nesting of < 5 > lists

Nesting

Similar to nesting of while loops, lists also support nesting

An element in a list is another list, so this is nesting of lists.

    schoolNames = [['Peking University','Tsinghua University'],
                    ['Nankai University','Tianjin University','Tianjin Normal University'],
                    ['Shandong University','Ocean University of China']]

- Application

There are three offices in a school. Now there are eight teachers waiting for the allocation of jobs. Please write a program to complete the random allocation.

#encoding=utf-8

import random

# Define a list to hold three offices
offices = [[],[],[]]

# Define a list to store the names of eight teachers
names = ['A','B','C','D','E','F','G','H']

i = 0
for name in names:
    index = random.randint(0,2)    
    offices[index].append(name)

i = 1
for tempNames in offices:
    print('Office%d The number of people is:%d'%(i,len(tempNames)))
    i+=1
    for name in tempNames:
        print("%s"%name,end='')
    print("\n")
    print("-"*20)