python列表的操作

定义一个列表

>>> name = ["a","b"]
>>> name
['a', 'b']
>>> name[0]
'a'

append追加

>>> name.append("c")
>>> 
>>> name
['a', 'b', 'c']

insert插入

>>> name.insert(1,0)
>>> 
>>> name
['a', 0, 'b', 'c']

extend列表之间的合并

>>> color = ["rend","yellow","green"]
>>> color
['rend', 'yellow', 'green']
>>> name.extend(color)
>>> name
['a', 0, 'b', 'c', 'rend', 'yellow', 'green']

列表嵌套

>>> name.insert(2,["e","f","g"])
>>> name
['a', 0, ['e', 'f', 'g'], 'b', 'c', 'rend', 'yellow', 'green']

del删除

>>> del name[2]
>>> 
>>> 
>>> name
['a', 0, 'b', 'c', 'rend', 'yellow', 'green']

pop 删除

>>> name.pop()  #默认删除最后一个元素并返回删除的值
'green'
>>> name
['a', 0, 'b', 'c', 'rend', 'yellow']

>>> name.pop(0) #删除指定索引并返回删除的值
'a'
>>> name
[0, 'b', 'c', 'rend', 'yellow']

remove删除

>>> address
['aaa', 'bbb', 'ccc']
>>> address.remove("aaa") #删除指定元素
>>> address
['bbb', 'ccc']
['bbb', 'ccc', 'eee', 'eee']
>>> address.remove("eee") #有相同元素，则删除第一个
>>> address
['bbb', 'ccc', 'eee']

clear清空

>>> color
['rend', 'yellow', 'green']
>>> color.clear()
>>> color
[]

索引修改

>>> name[0] = "first"
>>> 
>>> 
>>> name
['first', 'b', 'c', 'rend', 'yellow']

查操作

>>> name.index("b") #从左开始查第一个元素b的索引
1
>>> name.count("b") #计算元素b出现的次数
1
>>> "rend" in name
True

>>> help(name.remove)

切片，同时取多个元素

['first', 'b', 'rend', 'yellow']
>>> name[1:3] #顾头不顾尾
['b', 'rend']
>>> name[1:-1]
['b', 'rend']
>>> name[1:] #冒号后面全取
['b', 'rend', 'yellow']
>>> name[:3] #冒号前面全取
['first', 'b', 'rend']
>>> name[-1:-4]
[]
>>> name[-4:-1]
['first', 'b', 'rend']
>>> 
>>> name[-4:]
['first', 'b', 'rend', 'yellow']

步长

>>> name
['first', 'b', 'rend', 'yellow', 'c', 'd', 'e']
>>> 
>>> name[0:-1]
['first', 'b', 'rend', 'yellow', 'c', 'd']
>>> name[0:-1:1]
['first', 'b', 'rend', 'yellow', 'c', 'd']
>>> name[0:-1:2]
['first', 'rend', 'c']

>>> name[-1:-5:1]
[]
>>> name[-1:-5:-1] # 倒序切片,步长-1
['e', 'd', 'c', 'yellow']
>>> 

>>> name[:] #省略写法
['first', 'b', 'rend', 'yellow', 'c', 'd', 'e']
>>> name[0:-1] #不顾尾
['first', 'b', 'rend', 'yellow', 'c', 'd']
>>> name[0:-1:2] #步长为2取
['first', 'rend', 'c']
>>> name[::2] #头尾兼顾
['first', 'rend', 'c', 'e']
>>> name[::] #默认步长为1
['first', 'b', 'rend', 'yellow', 'c', 'd', 'e']
>>> name[::-1] #列表反转
['e', 'd', 'c', 'yellow', 'rend', 'b', 'first']


>>> n = "abcde"
>>> 
>>> n[::-1] #字符串反转
'edcba'

reverse反转

>>> name.reverse()
>>> name
['e', 'd', 'c', 'yellow', 'rend', 'b', 'first']

sort排序

>>> name.sort()
>>> 
>>> 
>>> name
['b', 'c', 'd', 'e', 'first', 'rend', 'yellow']

列表的for循环

>>> name
['b', 'c', 'd', 'e', 'first', 'rend', 'yellow']
>>> for i in name:
...   print(i)
... 
b
c
d
e
first
rend
yellow