python 列表（list）
字串可以修改嗎？
s = “123456789”
字串是不可變物件，屬於序列。可以使用索引訪問，索引可以是整數，也可以是負數，支援切片訪問等。列表也是Python內建的一種資料結構，屬於序列。
一、列表
1、列表定義
1）列表是python的一個內建資料結構
2）可以把列表看做一個容器
3）該容器被隔成不同的空間，每個空間可以放任何型別“物”
4）列表內物體只有前後的位置關係
5）列表每個格子中的“物”是可以替換的
6）列表是一個可變的序列
2、建立列表語法
----列表名 = [列表內容.......]
某些情況下，列表名 和“=”可以省略，列表可以為空列表
2）列表定義舉例
---[100,200,300]
--- L=[]
---L=["A","B","F","g"]
---L =[1,"hello",2,"world"]
---L =[1,2,[1,2,3,4,5],"y","i"]
---L =[1,2,(1,2,3),9]
----L =[1,2,3,4,{5,6,"y","i"},8]
----L =[1,2,3,4,{"name":"alex","age":12},8]
3、使用list函式建立列表
1)使用列表（list）函式建立列表
| 函式 | 說明 |
| list() | 生產一個空列表，等同於[] |
| list(iterable) | 用可迭代物件初始化一個列表 |
2)示例
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
L = list()
L = list("abc")
s = "suzhou"
P =list(s)
q =list([1,2,3])
print(L)
print(P)
print(q)
"""
['a', 'b', 'c']
['s', 'u', 'z', 'h', 'o', 'u']
[1, 2, 3]
Process finished with exit code 0
"""
4、列表運算
1)+運算
列表連結
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3] +["a","b","c"]
b = [9,10]
c = a+b
print(c)
"""
[1, 2, 3, 'a', 'b', 'c', 9, 10]
Process finished with exit code 0
"""
2）+=運算
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"a","b","c"]
a+=["alex","rose"]
print(a)
"""
[1, 2, 3, 'a', 'b', 'c', 'alex', 'rose']
Process finished with exit code 0
"""
3) *運算（複製）
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=["alex","rose"]*8
print(a)
"""
['alex', 'rose', 'alex', 'rose', 'alex', 'rose', 'alex', 'rose', 'alex', 'rose', 'alex', 'rose', 'alex', 'rose', 'alex', 'rose']
Process finished with exit code 0
"""
4） *=運算
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=["alex","rose"]*8
print(a)
"""
[1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3]
Process finished with exit code 0
"""
列表關係運算：返回True或者False
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3]
b=[1,2,3]
c=[4,5,6]
print(a!=b)
print(a==b)
print(a<c)
print(b>c)
"""
False
True
True
False
Process finished with exit code 0
"""
列表 in 和 not in 運算
如果物件在列表中返回True或者False
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3]
b=1
c=8
print(b in a)
print(c not in a)
"""
True
True
Process finished with exit code 0
"""
列表and,or,not 運算
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3]
b=[1]
c=[8]
print(a and b)
print(a or b)
print(not a)
"""
[1]
[1, 2, 3]
False
Process finished with exit code 0
"""
5、列表索引與切片訪問
1)l列表索引與切片訪問
索引從0開始，列表最後一個成員的索引為列表長度-1
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"alex",9,4]
b=a[0] #索引為負時，-1最後一個，向前類推-2就是倒數第二個
a[0]=8
c = a[-1]
print(a)
print(c)
"""
[8, 2, 3, 'alex', 9, 4]
4
Process finished with exit code 0
"""
列表切片slice
----切片語法同字串【起始：結束：步長】
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"alex",9,4,5,6,7,8]
b=a[1:9:2]
print(b)
c = a[0:-3]
print(c)
f =a[-3:]
print(f)
"""
[2, 'alex', 4, 6]
[1, 2, 3, 'alex', 9, 4, 5]
[6, 7, 8]
Process finished with exit code 0
"""
----通過切片獲取新列表
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"alex",9,4,5,6,7,8]
b=a[1:5]
print(b)
c = a[:] #複製列表
print(c)
"""
[2, 3, 'alex', 9]
[1, 2, 3, 'alex', 9, 4, 5, 6, 7, 8]
Process finished with exit code 0
"""
-----列表切片賦值
切片賦值可以一次修改對個列表元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"alex",9,4,5,6,7,8]
a[1:3] =["hello","world"]
print(a)
"""
[1, 'hello', 'world', 'alex', 9, 4, 5, 6, 7, 8]
Process finished with exit code 0
"""
切片賦值可以增加列表元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,"alex",9,4,5,6,7,8]
a[1:] =["hello","world","alex","rose"]
print(a)
"""
[1, 'hello', 'world', 'alex', 'rose']
Process finished with exit code 0
"""
列表切片賦值
切片賦值可以不替換任何元素情況下，為列表插入新元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1, 'hello', 'world', 'alex', 'rose']
a[2:2]=["a","b"]
print(a)
"""
[1, 'hello', 'a', 'b', 'world', 'alex', 'rose']
Process finished with exit code 0
"""
切片賦值可以刪除列表元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1, 'hello', 'world', 'alex', 'rose']
a[2:4]=[]
print(a)
"""
[1, 'hello', 'rose']
Process finished with exit code 0
"""
6、Python3中常用列表函式
1）len函式：可以用來得到序列的長度
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1, 'hello', 'world', 'alex', 'rose']
b = len(a)
print(b)
"""
5
Process finished with exit code 0
"""
2)max函式：可以用來得到序列最大值的元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2, 99,56,88]
b = max(a)
print(b)
"""
99
Process finished with exit code 0
"""
3）min函式：可以得到列表中最小的元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2, 99,56,88]
b = ["a","yy","dd"]
c =["a",1,"4"]
print(min(a))
print(min(b))
print(min(c)) #報錯
"""
1
a
print(min(c))
TypeError: '<' not supported between instances of 'int' and 'str'
Process finished with exit code 0
"""
4）sum函式
---可以得到列表中所有元素的和
---sum(列表【，起始值】)
---起始值可以省略，預設為0
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3]
b = sum(a)
print(b,type(b))
d = sum([b,10])
print(d)
"""
6 <class 'int'>
16
Process finished with exit code 0
"""
5）.index函式:得到列表中某個元素的索引（下標）
---L.index(value)
---value:要找的元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,33,88,9]
b = a.index(9) #相同的元素只會操作第一次出現的位置
print(b)
"""
5
Process finished with exit code 0
"""
6).append函式
----L.append(object)
----object要新增的元素
----返回None
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,33,88,9]
b = a.append("alex")
print(a)
print(b)
c = a.append([11,22])
print(a)
print(c)
"""
[1, 2, 3, 5, 6, 9, 10, 33, 88, 9, 'alex']
None
[1, 2, 3, 5, 6, 9, 10, 33, 88, 9, 'alex', [11, 22]]
None
Process finished with exit code 0
"""
7)合併列表（extend）
向列表追加另一個列表
----L.extend(iterable)
----iterable要新增的元素（可以迭代物件）
----返回None
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,33,88,9]
b = a.extend("alex")
print(a)
print(b)
c = a.extend(100)
print(a)
print(c)
"""
[1, 2, 3, 5, 6, 9, 10, 33, 88, 9, 'a', 'l', 'e', 'x']
None
c = a.extend(100)
TypeError: 'int' object is not iterable
Process finished with exit code 0
"""
跟元組一樣，用加號（+）將兩個列表加起來即可實現合併：
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
x=list(range(1, 13, 2))
x + ['b', 'a']
print(x)
"""
[1, 3, 5, 7, 9, 11, 'b', 'a']
Process finished with exit code 0
"""
對於已定義的列表，可以用extend方法一次性新增多個元素：
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
x=[1, 3, 5, 7, 9, 11]
x2=[3, 6, 1]
x.extend(x2)
print(x)
"""
[1, 3, 5, 7, 9, 11, 3, 6, 1]
Process finished with exit code 0
"""
需要說明的是：加號（+）執行列表的合併是非常浪費資源的，因為必須建立一個新列表並將所有物件複製過去，而用extend將元素附加到現有列表（尤其是在構建一個大列表時）就會好很多。
因此，在進行列表合併操作時，尤其是對於大資料量的列表合併，強烈建議使用extend函式。
8).insert函式：向列表指定位置插入元素
---L.insert(index,object)
---index:位置
---object要插入的元素
---返回None
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,33,88,9]
b = a.insert(2,["alex","rose"])
print(a)
print(b)
c = a.insert(5,100)
print(a)
print(c)
"""
[1, 2, ['alex', 'rose'], 3, 5, 6, 9, 10, 33, 88, 9]
None
[1, 2, ['alex', 'rose'], 3, 5, 100, 6, 9, 10, 33, 88, 9]
None
Process finished with exit code 0
"""
9).pop函式
---L.pop([index])
---刪除索引對應的元素，如果不加索引，預設刪除最後元素，同時返回移除元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,33,88,9]
b = a.pop()
print(a)
print(b)
c = a.pop(2)
print(a)
print(c)
d = a.pop(-1)
print(a)
print(d)
"""
[1, 2, 3, 5, 6, 9, 10, 33, 88]
9
[1, 2, 5, 6, 9, 10, 33, 88]
3
[1, 2, 5, 6, 9, 10, 33]
88
Process finished with exit code 0
"""
10）.remove函式：
---L.remove(x）
---從列表中刪除第一次出現在列表中的值
---返回None
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
b = a.remove(5)
print(a)
print(b)
c = a.remove("alex")
print(a)
print(c)
"""
[1, 2, 3, 6, 9, 10, 'alex', 33, 88, 9]
None
[1, 2, 3, 6, 9, 10, 33, 88, 9]
None
Process finished with exit code 0
"""
11）del 語句刪除列表元素
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
b = a.remove(5)
print(a)
print(b)
c = a.remove("alex")
print(a)
print(c)
"""
[1, 2, 3, 6, 9, 10, 'alex', 33, 88, 9]
None
[1, 2, 3, 6, 9, 10, 33, 88, 9]
None
Process finished with exit code 0
"""
12）.copy函式
---L.copy() 淺複製處解析
---複製此列表（只複製一層，不會複製深層物件）
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
b =a.copy()
print(a,id(a))
print(b,id(b))
c =a is b
print(c)
d =a
print(d,id(d))
"""
[1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9] 44549704
[1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9] 44549744
False
[1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9] 44549704
Process finished with exit code 0
"""
13）.reverse
---列表的反轉，只反轉排列順序，列表的值是不會改變的
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
print("反轉前的資料===》",a)
b =a.reverse()
print("反轉後的資料===》",a)
print(b)
"""
反轉前的資料===》 [1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9]
反轉後的資料===》 [9, 88, 33, 'alex', 10, 9, 6, 5, 3, 2, 1]
None
Process finished with exit code 0
"""
14）.sort
--Lsort(reverse = False)
---將列表的順序按值得小到大的順序進行排列
列表的sort方法可以實現就地排序（無需建立新物件，字串按首字母進行排序）：
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,72,3,45,6,9,10,33,88,9]
print("排序前的資料===》",a)
b =a.sort()
print("排序後的資料===》",a)
print(b)
s=['a','ab','3e','z']
print("排序前的資料===》",s)
g=s.sort()
print("排序後的資料===》",s)
"""
排序前的資料===》 [1, 72, 3, 45, 6, 9, 10, 33, 88, 9]
排序後的資料===》 [1, 3, 6, 9, 9, 10, 33, 45, 72, 88]
None
排序前的資料===》 ['a', 'ab', '3e', 'z']
排序後的資料===》 ['3e', 'a', 'ab', 'z']
Process finished with exit code 0
"""
sort有幾個很好用的選項，一個是次要排序鍵，即一個能夠產生可用於排序的值的函式。如可以通過長度對一組字串進行排序：
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
b=['a','nl','drz','mowgt','aa']
b.sort(key=len)
print(b)
"""
['a', 'nl', 'aa', 'drz', 'mowgt']
Process finished with exit code 0
"""再比如是否進行降序排列，如下面通過對首字母進行降序排列的示例：
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
b=['a','nl','drz','mowgt','aa']
b.sort(key= lambda x:x[0], reverse=True)
print(b)
"""
['nl', 'mowgt', 'drz', 'a', 'aa']
Process finished with exit code 0
"""
15）.clean：清空列表
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
print("清空前的資料===》",a)
b =a.clear()
print("清空後的資料===》",a)
print(b)
"""
清空前的資料===》 [1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9]
清空後的資料===》 []
None
Process finished with exit code 0
"""
7、列表的遍歷
1）使用while迴圈
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
i=0
while i<len(a):
print(a[i])
i+=1
"""
1
2
3
5
6
9
10
alex
33
88
9
Process finished with exit code 0
"""
2）使用for循壞
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
for i in a:
print(i)
"""
1
2
3
5
6
9
10
alex
33
88
9
Process finished with exit code 0
"""
8、列表複製
淺複製只複製一層
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a=[1,2,3,5,6,9,10,"alex",33,88,9]
b=a
print(b)
b[0]="rose"
print(b)
print(a)
print(a is b)
"""
[1, 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9]
['rose', 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9]
['rose', 2, 3, 5, 6, 9, 10, 'alex', 33, 88, 9]
True
Process finished with exit code 0
"""
深拷貝需要使用copy模組
---全部複製
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
import copy
a=[1,2,3,5,[6,9,10],"alex",33,88,9]
b = copy.deepcopy(a)
print(a,id(a))
print(b,id(b))
print(a is b)
b[4][0]=40
print(b)
"""
[1, 2, 3, 5, [6, 9, 10], 'alex', 33, 88, 9] 47178256
[1, 2, 3, 5, [6, 9, 10], 'alex', 33, 88, 9] 47179016
False
[1, 2, 3, 5, [6, 9, 10], 'alex', 33, 88, 9]
[1, 2, 3, 5, [40, 9, 10], 'alex', 33, 88, 9]
Process finished with exit code 0
"""
9、列表推導式語法
列表推導式是用可迭代物件依次生成列表內元素的方式
語法：
【表示式for 變數 in 可迭代物件】
或
【表示式 for 變數 in 可迭代物件 if 條件語句】
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
y = [ x**2 for x in range(1,10)]
print(y)
z =[x**2 for x in range(1,10) if x%2==1]
print(z)
"""
[1, 4, 9, 16, 25, 36, 49, 64, 81]
[1, 9, 25, 49, 81]
Process finished with exit code 0
"""
列表推導式巢狀語法
【表示式1 for 變數1 in 可迭代物件1 if 條件語句1 for 變數2 in 可迭代物件3 if 條件語句2】
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
y = [x*y for x in [2,3,5] for y in [7,11,13]]
print(y)
"""
[14, 22, 26, 21, 33, 39, 35, 55, 65]
Process finished with exit code 0
"""10、列表與字串
字串拆分與拼接
----S.split (sep = None,maxsplit = -1) --->list of string
-----S.join(iterable) ---->str
__author__ = 'Administrator'
# -*- coding:utf-8 -*-
a="beijing is captical !"
b =a.split(" ")
print(b)
c = a.split(maxsplit=1)
d = a.split(maxsplit=2)
f = a.split(maxsplit=3)
print(c)
print(d)
print(f)
print("-------join--------")
g="/"
print(g)
h = g.join(["C:","progrom file","python"])
print(h)
"""
['beijing', 'is', 'captical', '!']
['beijing', 'is captical !']
['beijing', 'is', 'captical !']
['beijing', 'is', 'captical', '!']
-------join--------
/
C:/progrom file/python
Process finished with exit code 0
"""
11、字串與列表比較
---列表 和字串都是序列，元素之間有先後關係
---字串中的每個元素只能儲存字元，而列表可以儲存任意型別
---字串是不可變的序列，而列表是可以改變的序列