在Python中提取列表列表的特定元素

Question

Here's a list: 这是一个清单：

foo=[(1, 2, {'weight': 1}), (1, 3, {'weight': 2}), (1, 4, {'weight': 3}), (`1 5, {'weight': 4}), (1, 6, {'weight': 5}), (1, 7, {'weight': 6})]

Say I wanted to extract a particular element of each list within foo and store it in a separate list. 假设我想在foo中提取每个列表的特定元素并将其存储在单独的列表中。

eg I wanted to extract 2nd element from each list, within foo and save it in the array labelled bar. 例如，我想从foo中的每个列表中提取第二个元素，并将其保存在标记为bar的数组中。

bar=[2,3,4,5,6,7]

How can this be done in Python 2.7x? 如何在Python 2.7x中完成？

Answer 1

>>> from operator import itemgetter
>>> map(itemgetter(1), foo))
[2, 3, 4, 5, 6, 7]

Answer 2

You can do that as: 你可以这样做：

bar = [i[1] for i in foo]
>>> print bar
[2,3,4,5,6,7]