一、列表簡介
列表是一系列按特定順序裴烈的元素組成,可以把任何東西放進列表中,列表其實相當於 C 語言中的數組,元素之間是沒有任何關係的。
一版情況下給列表指定一個複數的名稱,如 letters、digits、names之類的
bicycles=["trek","cannondale","redline","specialized"]
想要打印列表的話 直接打印即可
print(bicycles)
1、訪問列表元素
bicycles=["trek","cannondale","redline","specialized"]
print(bicycles[0])
運行結果:
trek
【在訪問列表元素的時候,python只返回該元素,而不包括引號 方括號等】
注意:訪問索引是從0開始的,而不是1開始;想要訪問最後一個元素可以使用:bicycles[-1]
bicycles[-2] 表示倒數第二個元素
bicycles[-3] 表示倒數第三個元素
2、修改、添加與刪除
2.1 修改
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
motorcycles[0] = 'ducati'
print(motorcycles)
運行結果:
['honda', 'yamaha', 'suzuki']
['ducati', 'yamaha', 'suzuki']
2.2 添加
在末尾添加
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
motorcycles.append('ducati')
print(motorcycles)
運行結果:
['honda', 'yamaha', 'suzuki']
['honda', 'yamaha', 'suzuki', 'ducati']
在列表中插入
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
motorcycles.insert(0,'ducati') # insert 可以在列表的任意位置添加新元素
print(motorcycles)
運行結果:
['honda', 'yamaha', 'suzuki']
['ducati', 'honda', 'yamaha', 'suzuki']
2.3 刪除元素
使用 del 語句刪除元素
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
del motorcycles[0]
print(motorcycles)
運行結果:
['honda', 'yamaha', 'suzuki']
['yamaha', 'suzuki']
使用 pop() 刪除元素
pop就相當於是 彈出,操作之後這個元素就不在列表中了
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
popped_motorcycle = motorcycles.pop()
print(motorcycles)
print(popped_motorcycle)
運行結果:
['honda', 'yamaha', 'suzuki']
['honda', 'yamaha']
suzuki
注意:被pop之後的元素不在列表中了
還可以pop指定位置的元素
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
popped_motorcycle = motorcycles.pop(0)
print(motorcycles)
print(popped_motorcycle)
運行結果:
['honda', 'yamaha', 'suzuki']
['yamaha', 'suzuki']
honda
如果不知道列表中要刪除的元素位置,只知道元素的值,那麼可以使用remove命令
motorcycles = ["honda","yamaha","suzuki"]
print(motorcycles)
motorcycles.remove('honda')
print(motorcycles)
運行結果:
['honda', 'yamaha', 'suzuki']
['yamaha', 'suzuki']
注意:remove只刪除第一個指定的值,想要刪除所有的 這個值的元素,就需要使用循環來完成
二、組織列表-排序
1、使用sort()對列表進行永久性排序
默認按照首字母的升序進行排序
cars = ["bmw","audi","toyota","subaru"]
cars.sort()
print(cars)
運行結果:
['audi', 'bmw', 'subaru', 'toyota']
如果想要降序排序,就需要將 reserve 參數設置成 true
cars = ["bmw","audi","toyota","subaru"]
cars.sort(reverse = True)
print(cars)
運行結果:
['toyota', 'subaru', 'bmw', 'audi']
2、使用 sorted() 對列表進行臨時排序
要保留列表元素原來的排列順序,同時以特定的順序呈現他們,就可以使用sorted()函數來完成
cars = ["bmw","audi","toyota","subaru"]
print(cars)
print(sorted(cars))
print(cars)
運行結果:
['bmw', 'audi', 'toyota', 'subaru']
['audi', 'bmw', 'subaru', 'toyota']
['bmw', 'audi', 'toyota', 'subaru']
可見 sort 沒有改變原列表的順序
3、反轉列表順序: reverse()
cars = ["bmw","audi","toyota","subaru"]
print(cars)
cars.reverse()
print(cars)
運行結果:
['bmw', 'audi', 'toyota', 'subaru']
['subaru', 'toyota', 'audi', 'bmw']
4、確定列表長度: len()
cars = ["bmw","audi","toyota","subaru"]
print(len(cars))
運行結果:
4