Python遍歷字典

1.遍歷key值

1 >>> d = {'Python':'astonishing', 'C++':'complicated', 'Java':'versatile'}
2 >>> for key in d:
3 ...     print(key + ':' + d[key])
4 ...
5 Python:astonishing
6 C++:complicated
7 Java:versatile

同理，可把下列代碼的d改為d.keys()

notice:python2除了上述兩種方法外，還可以寫為d.iterkeys()

2.遍歷value值

1 >>> for value in d:
2 ...     print(value)
3 ...
4 Python
5 C++
6 Java

同理，可把下列代碼的d改為d.values()

notice:python2除了上述兩種方法外，還可以寫為d.itervalues()

3.遍歷字典

 1 >>> for kv in d.items():
 2 ...     print(kv)
 3 ...
 4 ('Python', 'astonishing')
 5 ('C++', 'complicated')
 6 ('Java', 'versatile')
 7 >>> for k, v in d.items():#開始偷懶，縮寫k, v
 8 ...     print(k + ':' + v)
 9 ...
10 Python:astonishing
11 C++:complicated
12 Java:versatile

其實還有一種方法，用到了zip(元素對)使得我們可以像c/c++等語言一樣迴圈兩個變數

1 >>> for k, v in zip(d.keys(), d.values()):
2 ...     print(k + ':' + v)
3 ...
4 Python:astonishing
5 C++:complicated
6 Java:versatile

 關於zip的用法，詳見python cookbook:https://python3-cookbook.readthedocs.io/zh_CN/latest/c04/p11_iterate_over_multiple_sequences_simultaneously.html