用于在以列表的列表作为值的字典中搜索对象的Linq查询

我正在搜索一个有datetime类型键和值作为对象列表的排序字典。我需要找到的是字典中每个对象的最新值(基于对象的属性)。我的对象有3个属性:一个名称，一个值和一个创建日期。我的字典是按最近日期降序排列的。

我以某种方式得到了这个工作，但我确信有一个使用LINQ的快捷方式。请注意，我正在使用。NET 3.5 。你能帮帮我吗?请不要被下面的大量代码所推迟，因为我为了清晰起见添加了它，我只是在寻找一个linq查询来查询列表对象的列表。

下面的代码:

public void Should_link_recent_data_together()
{
    var data = TimeSeriesDataFactoryEx.GetData();
    var allAttributes = new List<string>()
    {
        TimeSeriesConstants.TOTAL_COST_CODE,
        TimeSeriesConstants.TOTAL_VALUE_CODE,
        TimeSeriesConstants.SOURCE_CODE
    };
    var latestList = new List<TimeSeries>();
    var allValues = data.Values.ToList();

    #region HOW DO I DO THIS USING LINQ?
    bool found = false;
    foreach (var attribute in allAttributes)
    {
        found = false;
        foreach (var tsData in allValues)
        {
            foreach (var ts in tsData)
            {
                if (ts.MetricName == attribute && !string.IsNullOrEmpty(ts.MetricValue))
                {
                    latestList.Add(ts);
                    found = true;
                    break;
                }
            }
            if (found)
                break;
        }
    }
    #endregion
    Assert.IsTrue(latestList.Count == 3);
    Assert.IsTrue(latestList.Where(x => x.MetricName == TimeSeriesConstants.TOTAL_COST_CODE).First().MetricValue == "1");
    Assert.IsTrue(latestList.Where(x => x.MetricName == TimeSeriesConstants.TOTAL_VALUE_CODE).First().MetricValue == "2");
    Assert.IsTrue(latestList.Where(x => x.MetricName == TimeSeriesConstants.SOURCE_CODE).First().MetricValue == "gp");
    Assert.IsTrue(latestList.Where(x => x.MetricName == TimeSeriesConstants.SOURCE_CODE).First().Quarter == DateTime.Today.AddMonths(-3));
}

internal class TimeSeriesDataFactoryEx
{
    public static SortedDictionary<DateTime?,List<TimeSeries>> GetData()
    {
        return new SortedDictionary<DateTime?, List<TimeSeries>>(new DateComparer())
        {
            {
                DateTime.Today, new List<TimeSeries>()
                {
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today,
                        MetricValue = "1",
                        MetricName = TimeSeriesConstants.TOTAL_COST_CODE
                    },
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today,
                        MetricValue = "2",
                        MetricName = TimeSeriesConstants.TOTAL_VALUE_CODE
                    },
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today,
                        MetricValue = "",
                        MetricName = TimeSeriesConstants.SOURCE_CODE
                    }
                }
            },
            {
                DateTime.Today.AddMonths(-3), new List<TimeSeries>()
                {
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today.AddMonths(-3),
                        MetricValue = "3",
                        MetricName = TimeSeriesConstants.TOTAL_COST_CODE
                    },
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today.AddMonths(-3),
                        MetricValue = "4",
                        MetricName = TimeSeriesConstants.TOTAL_VALUE_CODE
                    },
                    new TimeSeries()
                    {
                        Quarter = DateTime.Today.AddMonths(-3),
                        MetricValue = "gp",
                        MetricName =TimeSeriesConstants.SOURCE_CODE
                    }
                }
                }
        };
    }
}

{ Key = "1/1/1900", Value = List Of Objects, of which each has a DateTimeProperty }
...
{ Key = "1/4/1900", Value = List Of Objects, of which each has a DateTimeProperty }

var latestItems = data.SelectMany(kvp => 
    kvp.Value.OrderByDescending(value => value.Quarter).Take(1)
);