第3章 列表简介
本章目标：理解列表的概念，掌握创建、访问、修改、删除列表元素的方法，学会组织列表的常用操作。
3.1 列表是什么
列表 由一系列按特定顺序排列的元素组成。用方括号 [] 表示，逗号分隔元素。
python
bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles)
# ['trek', 'cannondale', 'redline', 'specialized']建议给列表指定复数名称 ，如
letters、digits、names。
3.1.1 访问列表元素
通过索引（从 0 开始）访问：
python
bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles[0]) # trek
print(bicycles[0].title()) # Trek（可对元素调用字符串方法）3.1.2 索引从 0 而不是 1 开始
python
bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles[1]) # cannondale（第二个元素）
print(bicycles[3]) # specialized（第四个元素）
# 负索引：-1 表示最后一个元素
`print(bicycles[-1]) # specialized`
`
print(bicycles[-2]) # redline（倒数第二个）`
`
print(bicycles[-3]) # cannondale`
`
`3.1.3 使用列表中的各个值
python
bicycles = ['trek', 'cannondale', 'redline', 'specialized']
message = "My first bicycle was a " + bicycles[0].title() + "."
print(message)
# My first bicycle was a Trek.3.2 修改、添加和删除元素
3.2.1 修改列表元素
直接通过索引赋值：
python
motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles[0] = 'ducati'
print(motorcycles)
# ['ducati', 'yamaha', 'suzuki']3.2.2 在列表中添加元素
append() --- 在末尾添加：
python
motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles.append('ducati')
print(motorcycles)
# ['honda', 'yamaha', 'suzuki', 'ducati']
# 常用模式：先建空列表，再 append
motorcycles = []
motorcycles.append('honda')
motorcycles.append('yamaha')
motorcycles.append('suzuki')
print(motorcycles)
# ['honda', 'yamaha', 'suzuki']insert() --- 在任意位置插入（指定索引和值）：
python
motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles.insert(0, 'ducati')
print(motorcycles)
# ['ducati', 'honda', 'yamaha', 'suzuki']
insert(0, 'ducati')在索引 0 处插入，原有元素右移。
3.2.3 从列表中删除元素
| 方法 | 用法 | 特点 |
|---|---|---|
del |
del list[index] |
删除后无法再访问该值 |
pop() |
list.pop() |
删除末尾元素并返回该值 |
pop(index) |
list.pop(index) |
删除任意位置元素并返回 |
remove() |
list.remove(value) |
按值删除第一个匹配项 |
del 语句 --- 按位置删除（不再需要该值）：
python
motorcycles = ['honda', 'yamaha', 'suzuki']
del motorcycles[0]
print(motorcycles)
# ['yamaha', 'suzuki']
del motorcycles[1]
print(motorcycles)
# ['honda', 'suzuki']pop() 方法 --- 删除并继续使用该值：
python
# 默认弹出末尾
motorcycles = ['honda', 'yamaha', 'suzuki']
popped_motorcycle = motorcycles.pop()
print(motorcycles) # ['honda', 'yamaha']
print(popped_motorcycle) # suzuki
# 使用弹出的值
`last_owned = motorcycles.pop()`
`
print("The last motorcycle I owned was a " + last_owned.title() + ".")`
`
`pop(index) --- 弹出任意位置：
python
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.判断标准：
- 删除后不再使用 →
del - 删除后还要使用 →
pop()
remove() --- 按值删除（只删第一个匹配项）：
python
motorcycles = ['honda', 'yamaha', 'suzuki', 'ducati']
motorcycles.remove('ducati')
print(motorcycles)
# ['honda', 'yamaha', 'suzuki']
# 可先用变量存储，删除后继续使用该值
too_expensive = 'ducati'
motorcycles.remove(too_expensive)
print("\nA " + too_expensive.title() + " is too expensive for me.")
# A Ducati is too expensive for me.⚠️
remove()只删除第一个匹配值。多个重复值需要用循环处理（第 7 章）。
3.3 组织列表
3.3.1 sort() --- 永久排序
python
cars = ['bmw', 'audi', 'toyota', 'subaru']
cars.sort()
print(cars)
# ['audi', 'bmw', 'subaru', 'toyota']
# 倒序排列
cars.sort(reverse=True)
print(cars)
# ['toyota', 'subaru', 'bmw', 'audi']
sort()永久修改列表顺序，不可恢复。
3.3.2 sorted() --- 临时排序
python
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)
# 倒序临时排序
`print(sorted(cars, reverse=True))`
`
`
sorted()返回排序后的副本，不修改原列表。
3.3.3 reverse() --- 反转列表
python
cars = ['bmw', 'audi', 'toyota', 'subaru']
cars.reverse()
print(cars)
# ['subaru', 'toyota', 'audi', 'bmw']
reverse()永久反转顺序，再次调用可恢复。
3.3.4 len() --- 获取列表长度
python
>>> cars = ['bmw', 'audi', 'toyota', 'subaru']
>>> len(cars)
43.4 使用列表时避免索引错误
IndexError: list index out of range --- 索引超出列表范围：
python
motorcycles = ['honda', 'yamaha', 'suzuki']
print(motorcycles[3]) # ❌ IndexError（只有索引 0, 1, 2）解决方法：
- 尝试将索引减 1
- 使用
-1访问最后一个元素（仅在列表非空时有效） - 将列表或其长度打印出来，查看实际内容
python
# 空列表使用 -1 也会出错
motorcycles = []
print(motorcycles[-1]) # ❌ IndexError动手试一试
3-1 姓名
python
names = ['Alice', 'Bob', 'Charlie']
print(names[0])
print(names[1])
print(names[2])3-2 问候语
python
names = ['Alice', 'Bob', 'Charlie']
print("Hello, " + names[0] + "!")
print("Hello, " + names[1] + "!")
print("Hello, " + names[2] + "!")3-3 自己的列表
python
commute = ['motorcycle', 'car', 'bike']
print("I would like to own a Honda " + commute[0] + ".")3-4 ~ 3-7 嘉宾名单系列
python
# 3-4 嘉宾名单
guests = ['Einstein', 'Mozart', 'Curie']
print("Dear " + guests[0] + ", please join me for dinner.")
print("Dear " + guests[1] + ", please join me for dinner.")
print("Dear " + guests[2] + ", please join me for dinner.")
# 3-5 修改嘉宾名单
print("\n" + guests[1] + " can't make it.")
guests[1] = 'Newton'
print("Dear " + guests[0] + ", please join me for dinner.")
print("Dear " + guests[1] + ", please join me for dinner.")
print("Dear " + guests[2] + ", please join me for dinner.")
# 3-6 添加嘉宾
print("\nI found a bigger table!")
guests.insert(0, 'Da Vinci')
guests.insert(2, 'Shakespeare')
guests.append('Tesla')
print("Dear " + guests[0] + ", please join me for dinner.")
print("Dear " + guests[1] + ", please join me for dinner.")
print("Dear " + guests[2] + ", please join me for dinner.")
print("Dear " + guests[3] + ", please join me for dinner.")
print("Dear " + guests[4] + ", please join me for dinner.")
print("Dear " + guests[5] + ", please join me for dinner.")
# 3-7 缩减名单
`print("\nSorry, I can only invite two people for dinner.")`
`
popped = guests.pop()`
`
print("Sorry " + popped + ", I can't invite you to dinner.")`
`
popped = guests.pop()`
`
print("Sorry " + popped + ", I can't invite you to dinner.")`
`
popped = guests.pop()`
`
print("Sorry " + popped + ", I can't invite you to dinner.")`
`
popped = guests.pop()`
`
print("Sorry " + popped + ", I can't invite you to dinner.")`
`
print("\nDear " + guests[0] + ", you're still invited.")`
`
print("Dear " + guests[1] + ", you're still invited.")`
`
del guests[0]`
`
del guests[0]`
`
print(guests) # []`
`
`3-8 放眼世界
python
places = ['Tokyo', 'Iceland', 'New Zealand', 'Egypt', 'Brazil']
print(places)
print(sorted(places))
print(places)
print(sorted(places, reverse=True))
print(places)
places.reverse()
print(places)
places.reverse()
print(places)
places.sort()
print(places)
places.sort(reverse=True)
print(places)3-9 晚餐嘉宾
python
guests = ['Einstein', 'Mozart', 'Curie', 'Newton', 'Da Vinci']
print("I invited " + str(len(guests)) + " guests to dinner.")3-10 尝试使用各个函数
python
languages = ['Python', 'Java', 'C', 'JavaScript', 'Ruby']
print(languages)
print(sorted(languages))
languages.sort()
print(languages)
languages.sort(reverse=True)
print(languages)
languages.reverse()
print(languages)
print(len(languages))
languages.append('Go')
languages.insert(0, 'Swift')
print(languages)
languages.pop()
languages.remove('Swift')
print(languages)3-11 有意引发错误
python
items = [1, 2, 3]
# print(items[3]) # ❌ IndexError
print(items[-1]) # ✅ 使用 -1 安全访问最后一个代码块汇总
python
# 创建列表
bicycles = ['trek', 'cannondale', 'redline', 'specialized']
# 访问元素（索引从 0 开始）
bicycles[0] # 第一个元素
bicycles[-1] # 最后一个元素
# 修改
motorcycles[0] = 'ducati'
# 添加
motorcycles.append('ducati') # 末尾
motorcycles.insert(0, 'ducati') # 指定位置
# 删除
del motorcycles[0] # 按索引删除（不使用值）
popped = motorcycles.pop() # 弹出末尾（使用值）
popped = motorcycles.pop(0) # 弹出任意位置
motorcycles.remove('ducati') # 按值删除（只删第一个）
# 排序
cars.sort() # 永久排序
cars.sort(reverse=True) # 永久倒序
sorted(cars) # 临时排序
sorted(cars, reverse=True) # 临时倒序
# 反转
cars.reverse()
# 长度
`len(cars)`
`
`常见错误 / 陷阱
| 错误类型 | 说明 | 解决 |
|---|---|---|
IndexError |
索引超出范围 | 索引从 0 开始，最大索引为 len(list) - 1 |
空列表 -1 |
空列表用 -1 也会出错 |
访问前检查列表是否为空 |
remove() 只删一个 |
重复值只删第一个 | 用循环处理 |
误用 sort() |
以为 sort() 不影响原列表 |
sort() 永久修改，sorted() 临时修改 |
复习要点
- 列表用
[]表示，元素用逗号分隔 - 索引从 0 开始，
-1访问最后一个 -
append()末尾添加，insert()任意位置插入 -
del/pop()/remove()三种删除方式的区别和适用场景 -
sort()永久排序 vssorted()临时排序 -
reverse()反转列表顺序 -
len()获取列表长度 - 避免
IndexError：最大索引 =len(list) - 1