每日Python五分钟2：列表简介

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1、列表

打印列表

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

输出

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

输出列表第一个位置元素

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

输出

trek

输出列表特定位置元素

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

输出

cannondale
specialized

通过将索引指定为-1，可让Python返回最后一个列表元素。类推，-2就是倒数第二个。

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

输出

specialized

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']

列表添加元素

末尾追加

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

输出

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

列表插入元素

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

输出

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

列表删除元素（del）

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

输出

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

方法pop()可删除列表末尾的元素，并让你能够接着使用它

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

输出

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

也可以使用pop()来删除任何位置的元素，只需在括号中指定要删除的元素的索引

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

输出

The first motorcycle I owned was a Honda.

根据值删除元素（若好多值相同，remove只能删除第一个指定的值）

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

输出

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

列表排序sort()

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

输出

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

按与字母顺序相反的顺序排列列表元素

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

输出

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

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)

输出

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']

调用sorted()后，列表元素的排列顺序没有变。如果要按与字母顺序相反的顺序显示列表，可以向sorted()传递参数reverse=True

倒着打印列表

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

输出

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

确定列表的长度

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

输出

4