>> for k, v in knights.items(): ... print(k, v) ... gallahad the pure robin the bra" />
牛骨文教育服务平台(让学习变的简单)

在字典中循环时,关键字和对应的值可以使用 iteritems() 方法同时解读出来:

>>> knights = {"gallahad": "the pure", "robin": "the brave"}
>>> for k, v in knights.items():
...     print(k, v)
...
gallahad the pure
robin the brave

在序列中循环时,索引位置和对应值可以使用 enumerate() 函数同时得到:

>>> for i, v in enumerate(["tic", "tac", "toe"]):
...     print(i, v)
...
0 tic
1 tac
2 toe

同时循环两个或更多的序列,可以使用 zip() 整体打包:

>>> questions = ["name", "quest", "favorite color"]
>>> answers = ["lancelot", "the holy grail", "blue"]
>>> for q, a in zip(questions, answers):
...     print("What is your {0}?  It is {1}.".format(q, a))
...
What is your name?  It is lancelot.
What is your quest?  It is the holy grail.
What is your favorite color?  It is blue.

需要逆向循环序列的话,先正向定位序列,然后调用 reversed() 函数:

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

要按排序后的顺序循环序列的话,使用 sorted() 函数,它不改动原序列,而是生成一个新的已排序的序列:

>>> basket = ["apple", "orange", "apple", "pear", "orange", "banana"]
>>> for f in sorted(set(basket)):
...     print(f)
...
apple
banana
orange
pear