如何对多个列表属性进行排序? [英] How to sort multiple list properties?
问题描述
我有列表列表myList,它具有1200万个元素.myClass具有两个属性,即."gt"和"gm".我想找到最大的"gt"元素,然后选择最小的"gm".例如:让 myList 如:(第一列是 gt 其他是 gm)
I have list list myList which has over 12 million elements. myClass has two properties ie. "gt" and "gm". I want to find maximum "gt" elements and choose that has min "gm". forexample: let myList such as:(first column is gt other is gm)
4 1
5 2
7 1
8 3
4 3
2 2
8 7
1 7
8 2
我想获取具有gt = 8,gm = 2的myClass元素.我可以从哪里开始?按有效的方式对gt降序进行排序?
I want to get the myClass element which has gt=8,gm=2. Where can I start?is sorting gt descending order an efficent way?
推荐答案
myList.OrderByDescending(x => x.gt)
.ThenBy(x => x.gm)
.First();
一种更有效,但读取量更少的方法是使用 Enumerable.Aggregate
,该方法将集合迭代一次,从而在O(n)时间内执行:
A more efficient, but less readbale way would be using Enumerable.Aggregate
which iterates the collection once, and thus executes in O(n) time:
var seed = myList.First()
myList.Aggregate(seed,
(max, item) => {
if(item.gt > max.gt)
return item;
if(item.gt == max.gt && item.gm < max.gm)
return item;
return max;
});
在采用更有效的方法之前,请同时进行两项测量并确保在可读性-性能之间进行权衡是值得的.
Before going with the more efficient approach, measure both and make sure the readability-performance trade-off is worth it.
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