【Python】9“切片和迭代“

>>>L = [1,2,3]
>>>L[0]
>>>L[1]
>>>L[2]

>>>L = []
>>>n = 2
>>>for i in range(n)
>>> L.append(L[i])
L

>>>list = [1,2,3,4,5]
>>>#取list集合中的第0个到第3个元素，如果是从0开始取，0可以省略
>>>list[0:3] 
[1, 2, 3]

>>>list = [1,2,3,4,5]
>>>#记住最后一个元素的索引是-1
>>> list[-1:]
[5]
>>> list[-5:]
[1, 2, 3, 4, 5]
>>> 

>>> temp = list(range(10))
>>> temp[:10:2]
[0, 2, 4, 6, 8]

>>> str  = 'abcdefg'
>>> str[0:3]
'abc'

>>> l = [1,2,3,4,5]
>>> for i in l:
...     print(i)
... 
1
2
3
4
5

>>> l = (1,2,3,4,5)
>>> for i in l:
...     print(i)
... 
1
2
3
4
5

>>> dict = {'name':'lily','age':'21','hight':161}
>>> for key in dict:
...     print(key)
... 
name
age
hight

>>> for value in dict.values():
...     print(value)
... 
lily
21
161

>>> for key,value in dict.items():
...     print(key,value)
... 
name lily
age 21
hight 161

>>> str = 'abcdefg'
>>> for ch in str:
...     print(ch)
... 
a
b
c
d
e
f
g

>>> for x,y in enumerate([1,2,3,4,5]):
...     print(x,':',y)
... 
0 : 1
1 : 2
2 : 3
3 : 4
4 : 5

>>> from collections import Iterable
>>> isinstance('abc',Iterable)
True
>>> isinstance('123',Iterable)
True
>>> isinstance(123,Iterable)
False
>>>