python-列表操作方法

創建列表

>>> a = 6
>>> b = 8
>>> t = [6,8]
>>> t
[6, 8]
>>> t=[a,b]
>>> t
[6, 8]
>>> t=[a+2,b-2]
>>> t
[8, 6]

>>> s='this is a string.' 
>>> t=list(s)
>>> t
['t', 'h', 'i', 's', ' ', 'i', 's', ' ', 'a', ' ', 's', 't', 'r', 'i', 'n', 'g', '.']

>>> t=[[1,2,3],[4,5,6],[7,8,9]]
>>> t[0][1]
2

列表排序

>>> t=[2,1,4,3,6,8,10]
>>> t.sort()
>>> t
[1, 2, 3, 4, 6, 8, 10]

列表與簡單賦值的區別

簡單賦值：

>>> a=1
>>> b=a
>>> b
1
>>> b=2
>>> a
1
>>> b
2

列表賦值

>>> t1=[1,2,3]
>>> t2=t1
>>> t2[0]=4
>>> t2
[4, 2, 3]
>>> t1
[4, 2, 3]

>>> t1=[1,2,3]
>>> t2=t1[:]
>>> t2[0]=4
>>> t1
[1, 2, 3]
>>> t2
[4, 2, 3]

>>> t1=[1,2,3,4,5,6,7,8,9]
>>> t2=t1[2:4]
>>> t2
[3, 4]
>>> t1
[1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> t1[2:4]=[10,20]
>>> t1
[1, 2, 10, 20, 5, 6, 7, 8, 9]

>>> t1[2:4]=[10,20,30]
>>> t1
[1, 2, 10, 20, 30, 5, 6, 7, 8, 9]

>>> t1=[1,2,3,4,5,6,7,8,9]
>>> t1[2:4]=[]
>>> t1
[1, 2, 5, 6, 7, 8, 9]

del()：刪除列表中某一位置的元素

>>> t1=[1,2,3,4,5,6,7,8,9]
>>> del(t1[2])
>>> t1
[1, 2, 4, 5, 6, 7, 8, 9]
>>> del t1[2]
>>> t1
[1, 2, 5, 6, 7, 8, 9]

append()： 在列表最後添加一個元素

>>> t=[1,2,3,4]
>>> t.append(5)
>>> t
[1, 2, 3, 4, 5]

>>> t=[1,2,3,4]
>>> t.append([5,6])
>>> t
[1, 2, 3, 4, [5, 6]]

extend()：在列表最後添加一個列表中的元素

>>> t=[1,2,3,4]
>>> t.extend([6,7,8])
>>> t
[1, 2, 3, 4, 6, 7, 8]

extend()等效於加號“+”

insert()：在特定位置前面添加一個元素

>>> t=[1,2,3,4]
>>> t.insert(1,9)
>>> t
[1, 9, 2, 3, 4]

remove()：刪除列表中的某一值

>>> t=[1,2,3,4,5]
>>> t.remove(2)
>>> t
[1, 3, 4, 5]

pop()：刪除列表中最後一個值，並返回該值

>>> t=[1,2,3,4,5]
>>> t.pop()
5
>>> t
[1, 2, 3, 4]

>>> t=[1,2,3,4,5]
>>> t.pop(1)	#刪除列表中某一位置的值，並返回該值
2
>>> t
[1, 3, 4, 5]

reverse()：反轉列表

>>> t=[1,2,3,4,5]
>>> t.reverse()
>>> t
[5, 4, 3, 2, 1]

index()：查找列表中某一元素的位置，返回其第一次出現的位置

>>> t=[1,2,3,4,5]
>>> t.index(9)
Traceback (most recent call last):
  File "<pyshell#309>", line 1, in <module>
    t.index(9)
ValueError: 9 is not in list
>>> t.index(2)
1
>>> t.index(1)
0