5.6. 循环技巧

最后更新于:2022-04-01 00:48:00

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 ~~~
';