1、在字典中，用items()取出键和对应值

>>> king = {'name':'zxb','sex':'man','age':'18'}
>>> for k,v in king.items():
...     print(k,v)
...
name zxb
sex man
age 18
>>>

2、在序列中循环时，使enumerate()函数可以同时取出位置索引和对应值

>>> arr = ['a','b','c']
>>> for i,v in enumerate(arr):
...     print(i,v)
...
0 a
1 b
2 c
>>>

3、同时循环两个或多个序列时，用zip()函数可以将其内的元素一一匹配

>>> questions = ['name','age','sex']
>>> answers = ['zxb','18','man']
>>> for q,a in zip(questions,answers):
...     print('what is your {0}? It is {1}'.format(q,a))
...
what is your name? It is zxb
what is you rage? It is 18
what is your sex? It is man
>>>

4、使用reverse函数逆向循环序列

>>> for i in reversed(range(1,10,2)):
...     print(i)
...
9
7
5
3
1
>>>

5、按指定顺序循环序列，可以用sorted()函数，在不改动原序列基础上，返回一个新的序列

>>> zero = ['a','z','b','e','c']
>>> for i in sorted(zero):
...     print(i)
...
a
b
c
e
z
>>>

6、使用set()去除列表中的重复元素。使用sorted()加set()则按排序后的顺序，循环遍历序列中的唯一元素

>>> zero = ['a','z','b','e','c','a','c']
>>> for i in sorted(set(zero)):
...     print(i)
...
a
b
c
e
z
>>>

7、一般来说，在循环中修改列表的内容时，创建新列表比较简单

>>> import math
>>> arr = [56.5,float('NaN'),32.3]
>>> newArr = []
>>> for value in arr:
...     if not math.isnan(value):
...             newArr.append(value)
...
>>> newArr
[56.5, 32.3]
>>>