Question

我有一个字典，其中键是DateTime。我需要在字典中找到最接近给定日期时间的2个条目。

所以，我有

Dictionary<DateTime, double> columnInfos = new Dictionary<DateTime, double>();
foreach (var activity in activities)
{

    DateTime activityDate = activity.ActivityDateTime;

    // Get the 2 entries in the columnInfos dict that activityDate falls between

}

我打算在字典中循环，但这真的是最好的方式吗？＆gt;任何人都有更好的解决方案吗？

由于

Answer 1

这应该有效。 index-1和index+1将成为日期列表中立即小于和大于相关日期的位置。

SortedDictionary<DateTime, double> columnInfos = new SortedDictionary<DateTime, double>();

List<KeyValuePair<DateTime, double>> columnInfosList = columnInfos.ToList();

foreach (var activity in activities)
{
    DateTime activityDate = activity.ActivityDateTime;

    for (int index = 1; index < columnInfosList.Count(); index++)
    {
         if (columnInfosList[index-1].Key < activityDate && columnInfosList[index+1].Key > activityDate)
         {
              // do something with columnInfos[index-1] and columnInfos[index+1] then break so you stop searching
         }
    }
}

Answer 2

如果您可以将Dictionary<T, T>更改为SortedDictionary<T, T>，则可以编写如下函数：

private List<DateTime> FallBetween(SortedDictionary<DateTime, double> columns, DateTime activityDate)
{
    var keys = new List<DateTime>(columns.Keys);
    int index = ~(keys.BinarySearch(activityDate));

    var dates = new List<DateTime>();

    try
    {
        dates.Add(keys[index]);
    } catch { }

    try
    {
        dates.Add(keys[index - 1]);
    } catch { }

    return dates;
}

并称之为：

SortedDictionary<DateTime, double> columnInfos = new SortedDictionary<DateTime, double>();

columnInfos.Add(DateTime.Now, 1);
columnInfos.Add(DateTime.Now.AddDays(-2), 2);
columnInfos.Add(DateTime.Now.AddDays(-4), 3);
columnInfos.Add(DateTime.Now.AddDays(2), 4);
columnInfos.Add(DateTime.Now.AddDays(4), 5);

// dates will return a list containing two dates.
// Now - 2 days and Now - 4 days.
var dates = FallBetween(columnInfos, DateTime.Now.AddDays(-3));

// date will return a list containing only one date
// because there is only one nearing neighbor.
var date = FallBetween(columnInfos, DateTime.Now.AddDays(30));

查找2个日期日期时间从字典之间下降

2 个答案: