Python 编程从入门到实践-chapter3

列表

列表是什么

列表由一系列特定顺序排序的元素组成。元素之间可以没有任何关系。

示例：

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

输出 [‘trek’, ‘cannondale’, ‘redline’, ‘specialized’]

访问元素

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

输出 trek

修改、添加和删除元素

修改列表元素

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

motorcycles[0] = 'ducati'
print(motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘ducati’, ‘yamaha’, ‘suzuki’]

在列表中添加元素

在列表的末尾插入

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

motorcycles.append('ducati')
print(motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘honda’, ‘yamaha’, ‘suzuki’，’ducati’]

在列表特定的位置上插入

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

motorcycles.insert(0, 'ducati')
print(motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘honda’, ‘yamaha’, ‘suzuki’，’ducati’]

从列表中删除数据

使用 del 语句删除元素

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

del motorcycles[0]
print(motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘suzuki’, ‘ducati’]

使用 pop() 删除元素

默认删除列表中最后一个元素

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

poped_motorcycles = motorcycles.pop()
print(motorcycles)
print(poped_motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘honda’, ‘yamaha’] suzuki

删除列表特定位置的元素

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

poped_motorcycles = motorcycles.pop(0)
print(motorcycles)
print(poped_motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘yamaha’, ‘suzuki’] honda

根据值删除元素

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

motorcycles.remove('honda')
print(motorcycles)

输出

[‘honda’, ‘yamaha’, ‘suzuki’] [‘yamaha’, ‘suzuki’]

管理列表

使用 sort() 方法对列表进行永久排序

默认按照字典序升序的方式进行排序

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

输出 [‘audi’, ‘bmw’, ‘subaru’, ‘toyota’]

传入 reverse=True 按照字典序降序的方式进行排序

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

输出 [‘toyota’, ‘subaru’, ‘bmw’, ‘audi’]

使用 sorted() 函数对列表进行临时排序

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

输出 [‘audi’, ‘bmw’, ‘subaru’, ‘toyota’]

注意：不会改变原始列表

反向打印列表

使用 reverse() 方法

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

输出 [‘subaru’, ‘toyota’, ‘audi’, ‘bmw’]

确定列表的长度

使用 len() 函数

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