基本資料型別——列表
阿新 • • 發佈:2021-08-02
列表(list)
- 通過list建立物件,li = [1, 2, "age", "umbrella", [19, 10], "gxgd"]
中括號括起來
,分割每個元素
列表中的元素可以是數字、字串、列表、布林值(所有的值都能放進去)
“集合”內部可放置任何東西
可以通過索引取值,如:print(li[2])可獲取列表內第二個元素,索引取值可以一直往裡找
li = [1,12,9,"age",["雨傘",["19",10],"雨衣"],"umbrella","clothes"]
v = li[4][1][0][1]
print(v)
也支援切片取值,結果也是列表,如:print(li[3:-1])
支援for迴圈和while迴圈
li = [1, 2, "age", "umbrella", [19, 10], "gxgd"]
for item in li:
print(item)
列表元素可以被修改,索引、切片皆可用
li = [1, 2, "age", "umbrella", [19, 10], "gxgd"]
li[2] = [11, 22, 33]
li[1:3] = [120, 90]
print(li)
列表元素可以刪除,如:del li[1]——索引:某個位置元素的修改,del li[1:3] ——切片:某段元素修改
支援用 in 判斷某元素是否在列表內
li = [1, 2, "age", "umbrella", [19, 10], "gxgd"]
v = 120 in li
print(v)
- 將字串等轉化為列表 list (內部執行for迴圈,所以數字不行)
v = "umbrella" new_li = list(v) print(new_li)
- 列表元素合併成字串
同時包含數字和字串時——自己寫for迴圈
li = [11,22,33,"125","umbrella"]
v = " "
for i in li:
v = v + str(i)
print(v)
只有字串時——join
li = ["125","umbrella"]
v = "".join(li)
print(v)
list類中的方法:
- append() 在原來值後面追加新值,追加值可以是字串、列表、數字
li = ["125","umbrella"] v = li.append(5) print(v) print(li)
- clear() 清空列表
li = ["125","umbrella"]
li.clear()
print(li)
- copy() 淺拷貝
li = ["125","umbrella"] v = li.copy() print(v)
- count() 計算元素出現個數
li = ["125","umbrella","125",125,75] v1 = li.count("125") v2 = li.count(125) print(v1,v2)
- extend() 擴充套件元列表,括號裡的引數放可迭代物件(列表、字串等可進行for迴圈的)。注意區分append,append將括號內容作為一個整體放到列表最後;extend做了一個for迴圈,將元素挨個依次放入
li = ["125","umbrella","125",125,75] li.append([666,"雨傘"]) print(li)
li = ["125","umbrella","125",125,75] li.extend([666,"雨傘"]) print(li)
- index() 根據值獲取當前索引位置,預設從左往右找
li = [125,"125","umbrella","125",125,75] v = li.index(125) print(v)
- insert() 在指定索引位置插入元素
li = [125,"125","umbrella","125",125,75] li.insert(0,"fighting") print(li)
- pop() 刪除某個索引的值(未指定索引情況下預設刪最後一個),可獲得到刪掉的值
li = [125,"125","umbrella","125",125,75] v = li.pop(1) print(li) print(v)
- remove() 刪除列表中的某個指定值,預設左邊優先(PS:刪除方式總結——pop;remove;clear;del li[0] 索引刪;del li[1:2] 切片刪 )
li = [125,"125","umbrella","125",125,75] li.remove(125) print(li)
- reverse() 將當前列表進行反轉
li = [125,"125","umbrella","125",125,75] li.reverse() print(li)
- sort() 對列表進行排序(可從大到小或從小到大)
li = [125,1,8,9,125,75] li.sort() print(li)