从python的dicts列表中选择最高值

Question

在一系列dicts列表中:

 A = [
       [{'x': 1, 'y': 0}, {'x': 2, 'y': 3}, {'x': 3, 'y': 4}, {'x': 4, 'y': 7}],

       [{'x': 1, 'y': 0}, {'x': 2, 'y': 2}, {'x': 3, 'y': 13}, {'x': 4, 'y': 0}],

       [{'x': 1, 'y': 20}, {'x': 2, 'y': 4}, {'x': 3, 'y': 0}, {'x': 4, 'y': 8}]

     ]

我需要从每个dicts列表中检索最高的'y'值...所以结果列表将包含:

 Z = [(4, 7), (3,13), (1,20)]

在A中,'x'是每个字典的关键,而'y'是每个字典的值.

有任何想法吗？谢谢.

Answer 1

max接受可选key参数.

A = [
    [{'x': 1, 'y': 0}, {'x': 2, 'y': 3}, {'x': 3, 'y': 4}, {'x': 4, 'y': 7}],
    [{'x': 1, 'y': 0}, {'x': 2, 'y': 2}, {'x': 3, 'y': 13}, {'x': 4, 'y': 0}],
    [{'x': 1, 'y': 20}, {'x': 2, 'y': 4}, {'x': 3, 'y': 0}, {'x': 4, 'y': 8}]
]

Z = []
for a in A:
    d = max(a, key=lambda d: d['y'])
    Z.append((d['x'], d['y']))
print Z

UPDATE

建议 - JF Sebastian:

from operator import itemgetter
Z = [itemgetter(*'xy')(max(lst, key=itemgetter('y'))) for lst in A]

Answer 2

我会用itemgetter和max的key说法:

from operator import itemgetter

pair_getter = itemgetter('x', 'y')
[pair_getter(max(d, key=itemgetter('y'))) for d in A]