Select 使用 lambda 从并发字典中记录

Question

我有一个以日期时间为键和整数值的并发字典。每半小时有一个新条目，我有过去一周的数据，我想 select 特定日期的最高整数值。有关如何执行此操作的任何建议？

Answer 1

类似于：

var value = dictionary.Where(x => x.Key.Day == 5).Max(x=>x.Value);

Answer 2

一种可能性是按日期对并发字典中的值进行分组：

var dic = new ConcurrentDictionary<DateTime, int>();
dic[new DateTime(2015, 4, 5, 7, 0, 1)] = 1;
dic[new DateTime(2015, 4, 5, 7, 0, 2)] = 2;
dic[new DateTime(2015, 4, 5, 7, 0, 3)] = 3;
dic[new DateTime(2015, 4, 6, 7, 0, 1)] = 5;
dic[new DateTime(2015, 4, 6, 7, 0, 2)] = 6;
dic[new DateTime(2015, 4, 6, 7, 0, 3)] = 7;

var searchDay = new DateTime(2015, 4, 5);

// Find the values corresponding to the specified day
var dates = dic.GroupBy(item => item.Key.Date).FirstOrDefault(x => x.Key == searchDay.Date);
if (dates != null)
{
    int max = dates.Max(x => x.Value);
    // That's the maximum value for the specified day
}

Select 使用 lambda 从并发字典中记录

Select records from concurrent dictionary using lambda

c#

vb.net

lambda