Question

我需要找到最大值，例如：

[(12, 0.95), (15, 0.92), (20, 0.90), (12, 0.88), (15, 0.98), (12, 0.89)]

输出最大值对应于id：

[(12, 0.95), (15, 0.98), (20, 0.90)]

如何在python中实现这一目标？

任何建议！谢谢你的帮助

Answer 1

仅使用基础知识：

data = [(12, 0.95), (15, 0.92), (20, 0.90), (12, 0.88), (15, 0.98), (12, 0.89)]

result_dict = {}
for id_num, value in data:
    result_dict[id_num] = max(value, result_dict.get(id_num, value))

result = sorted(result_dict.items())

print(result)

如果循环中的部分令人困惑，可以采用其他方式编写它：

if id_num in result_dict:
    result_dict[id_num] = max(result_dict[id_num], value)
else:
    result_dict[id_num] = value

或

if id_num in result_dict:
    if value > result_dict[id_num]:
        result_dict[id_num] = value
else:
    result_dict[id_num] = value

或

if id_num not in result_dict or value > result_dict[id_num]:
    result_dict[id_num] = value

或

if id_num > result_dict.get(id_num, value):
    result_dict[id_num] = value

Answer 2

排序，groupby和max！

import itertools
import operator

data = [(12, 0.95), (15, 0.92), (20, 0.90), (12, 0.88), (15, 0.98), (12, 0.89)]
sorted_data = sorted(data)
groups = itertools.groupby(sorted_data, key=operator.itemgetter(0))
result = [max(group) for _, group in groups]

itertools.groupby获取一个排序的项目列表，按一些关键函数对它们进行分组（在本例中我们使用operator.itemgetter(0)），并为您提供一个形式的迭代器：

[(keyfunc_result, [list_of_results...], ... ]

如何找到最大值？

2 个答案: