列表简介

一.列表是什么

bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles)

['trek', 'cannondale', 'redline', 'specialized']

1.访问列表元素

bicycles = ['trek', 'cannondale', 'redline', 'specialized'] 
print(bicycles[0])

trek

2.索引从0而不是1开始

bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles[1])
print(bicycles[3])

cannondale
specialized

Python为访问最后一个列表元素提供了一种特殊语法。通过将索引指定为-1 ，可让Python返回最后一个列表元素：

bicycles = ['trek', 'cannondale', 'redline', 'specialized'] 
print(bicycles[-1])

3.使用列表中的各个值

bicycles = ['trek', 'cannondale', 'redline', 'specialized'] 
message = "My first bicycle was a " + bicycles[0].title() + "." 
print(message)

My first bicycle was a Trek.

二.修改、添加和删除元素

1.修改列表元素

motorcycles = ['honda', 'yamaha', 'suzuki'] 
print(motorcycles)
motorcycles[0] = 'ducati' 
print(motorcycles)

['honda', 'yamaha', 'suzuki']
['ducati', 'yamaha', 'suzuki']

2.在列表中添加元素

①在列表末尾添加元素

motorcycles = ['honda', 'yamaha', 'suzuki'] 
print(motorcycles)
motorcycles.append('ducati')
print(motorcycles)

['honda', 'yamaha', 'suzuki']
['honda', 'yamaha', 'suzuki', 'ducati']

②在列表中插入元素

motorcycles = ['honda', 'yamaha', 'suzuki'] 
motorcycles.insert(0, 'ducati') 
print(motorcycles)

['ducati', 'honda', 'yamaha', 'suzuki']

3.从列表中删除元素

①使用del语句删除元素

motorcycles = ['honda', 'yamaha', 'suzuki']
print(motorcycles) 
del motorcycles[0] 
print(motorcycles)

['honda', 'yamaha', 'suzuki']
['yamaha', 'suzuki']

②使用方法pop（）删除元素

motorcycles = ['honda', 'yamaha', 'suzuki'] 
print(motorcycles) 
popped_motorcycle = motorcycles.pop() 
print(motorcycles) 
print(popped_motorcycle)

['honda', 'yamaha', 'suzuki']
['honda', 'yamaha']
suzuki

③弹出列表中任何位置处的元素

motorcycles = ['honda', 'yamaha', 'suzuki'] 
first_owned = motorcycles.pop(0) 
print('The first motorcycle I owned was a ' + first_owned.title() + '.')

The first motorcycle I owned was a Honda.

④根据值删除元素

motorcycles = ['honda', 'yamaha', 'suzuki', 'ducati']
print(motorcycles) 
motorcycles.remove('ducati')
print(motorcycles)

['honda', 'yamaha', 'suzuki', 'ducati'] 
['honda', 'yamaha', 'suzuki']

三.组织列表

1.使用方法sort（）对列表进行永久性排序

cars = ['bmw', 'audi', 'toyota', 'subaru'] 
cars.sort()
print(cars)

['audi', 'bmw', 'subaru', 'toyota']

2.使用函数sorted（）对列表进行临时排序

cars = ['bmw', 'audi', 'toyota', 'subaru']
print("Here is the original list:")  
print(cars) 
print("\nHere is the sorted list:")  
print(sorted(cars)) 
print("\nHere is the original list again:")
print(cars)

Here is the original list:
['bmw', 'audi', 'toyota', 'subaru'] 
Here is the sorted list:  
['audi', 'bmw', 'subaru', 'toyota'] 
Here is the original list again: 
['bmw', 'audi', 'toyota', 'subaru']

3.倒着打印列表

cars = ['bmw', 'audi', 'toyota', 'subaru']
print(cars) 
cars.reverse() 
print(cars)

['bmw', 'audi', 'toyota', 'subaru']
['subaru', 'toyota', 'audi', 'bmw']

4.确定列表的长度

>>> cars = ['bmw', 'audi', 'toyota', 'subaru'] 
>>> len(cars)
4

操作列表

一.遍历整个列表

magicians = ['alice', 'david', 'carolina'] 
for magician in magicians: 
    print(magician)

alice 
david 
carolina

1.在for循环中执行更多的操作

magicians = ['alice', 'david', 'carolina'] 
for magician in magicians: 
    print(magician.title() + ", that was a great trick!"

Alice, that was a great trick!
David, that was a great trick!
Carolina, that was a great trick!

2.在for循环结束后执行一些操作

magicians = ['alice', 'david', 'carolina'] 
for magician in magicians:   
    print(magician.title() + ", that was a great trick!")    
    print("I can't wait to see your next trick, " + magician.title() + ".\n") 
print("Thank you, everyone. That was a great magic show!")

Alice, that was a great trick!
I can't wait to see your next trick, Alice.
David, that was a great trick!
I can't wait to see your next trick, David.
Carolina, that was a great trick!
I can't wait to see your next trick, Carolina. 
Thank you, everyone. That was a great magic show!

二.创建数值列表

1.使用函数range（）

for value in range(1,5):
    print(value)

1
2 
3 
4

2.使用range（）创建数字列表

要创建数字列表，可使用函数list()将range()的结果直接转换为列表。如果将range() 作为list() 的参数，输出将为一个数字列表。

numbers = list(range(1,6)) 
print(numbers)

[1, 2, 3, 4, 5]

even_numbers = list(range(2,11,2)) 
print(even_numbers)

在这个示例中，函数range() 从2开始数，然后不断地加2，直到达到或超过终值（11），因此输出如下：

[2, 4, 6, 8, 10]

3.对数字列表执行简单的统计运算

>>> digits = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
>>> min(digits) 
0 
>>> max(digits)
9 
>>> sum(digits)
45

4.列表解析

squares = [value**2 for value in range(1,11)] 
print(squares)

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

三.使用列表的一部分

1.切片

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
print(players[0:3])

['charles', 'martina', 'michael']

players = ['charles', 'martina', 'michael', 'florence', 'eli']
print(players[:4])

['charles', 'martina', 'michael', 'florence']

players = ['charles', 'martina', 'michael', 'florence', 'eli']
print(players[2:])

['michael', 'florence', 'eli']

2.遍历切片

players = ['charles', 'martina', 'michael', 'florence', 'eli']
print("Here are the first three players on my team:") 
for player in players[:3]:   
    print(player.title())

Here are the first three players on my team:
    Charles
    Martina
    Michael

3.复制列表

my_foods = ['pizza', 'falafel', 'carrot cake'] 
friend_foods = my_foods[:] 
print("My favorite foods are:") 
print(my_foods)
print("\nMy friend's favorite foods are:") 
print(friend_foods)

My favorite foods are:
['pizza', 'falafel', 'carrot cake']
My friend's favorite foods are:
['pizza', 'falafel', 'carrot cake']

四.元组

1.定义元组

dimensions = (200, 50) 
print(dimensions[0])  
print(dimensions[1])

200
50

dimensions = (200, 50) 
dimensions[0] = 250

Traceback (most recent call last): 
    File "dimensions.py", line 3, in <module> 
    dimensions[0] = 250 
    TypeError:'tuple' object does not support item assignment

2.遍历元组中的所有值

dimensions = (200, 50) 
for dimension in dimensions: 
    print(dimension)

200
50

3.修改元组变量

dimensions = (200, 50) 
print("Original dimensions:")
for dimension in dimensions: 
    print(dimension)
dimensions = (400, 100) 
print("\nModified dimensions:")
for dimension in dimensions:   
    print(dimension)

Original dimensions:
200
50
Modified dimensions:
400
100