如何找到最大值？

Question

我需要找到例如值的最大值：

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

输出最大值与ID对应：

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

我怎样才能在Python实现这一目标？

任何建议！感谢您的帮助

Answer 1

只需使用基础知识：

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) 

如果环路内的部分是混乱的，这里有其他的方式来写它：

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采取项目的排序列表，通过一些关键功能组他们（在这种情况下，我们使用operator.itemgetter(0)），并为您提供以下形式的迭代器：

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