python札记-集合迭代技术
python笔记---集合迭代技术
>>> basket = ['apple', 'orange', 'apple', 'pear', 'orange', 'banana'] >>> for f in sorted(set(basket)): ... print(f) ... apple banana orange pear
集合迭代技术
使用字典对象的items()方法可以得到键值对序列。
>>> knights = {'gallahad': 'the pure', 'robin': 'the brave'} >>> for k, v in knights.items(): ... print(k, v) ... gallahad the pure robin the brave
使用方法enumerate()可以得到序列的下标和值得序列。
>>> for i, v in enumerate(['tic', 'tac', 'toe']): ... print(i, v) ... 0 tic 1 tac 2 toe
可以通过zip()方法同时迭代多个序列。
>>> 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.
可以同个reversed()翻转一个序列。
>>> for i in reversed(range(1, 10, 2)): ... print(i) ... 9 7 5 3 1
通过sorted()可以排序一个序列。