c# - 如果日期相差一天，则合并列表元素

Question

我有一个看起来像这样的列表。如果日期相隔 1 天(“2022, 01, 01”和“2022, 01, 02)，我需要合并此列表元素，它们的费率、roomTypeId 和 Accessibility 完全相同。DateFrom 和 DateTo 始终相同在我给出的列表中，每个可用性代表一天。

             new Availability
            {
                Accessibility = 1,
                RoomTypeId = "12345",
                Rate = 50,
                DateFrom = new DateTime(2022, 01, 01),
                DateTo = new DateTime(2022, 01, 01)
            },
                new Availability
            {
                Accessibility = 1,
                RoomTypeId = "12345",
                Rate = 50,
                DateFrom = new DateTime(2022, 01, 02),
                DateTo = new DateTime(2022, 01, 02)
            },
                new Availability
            {
                Accessibility = 1,
                RoomTypeId = "12345",
                Rate = 100,
                DateFrom = new DateTime(2022, 01, 04),
                DateTo = new DateTime(2022, 01, 04)
            },
                new Availability
            {
                Accessibility = 6,
                RoomTypeId = "12345",
                Rate = 100,
                DateFrom = new DateTime(2022, 01, 05),
                DateTo = new DateTime(2022, 01, 05)
            },
                new Availability
            {
                Accessibility = 6,
                RoomTypeId = "12345",
                Rate = 100,
                DateFrom = new DateTime(2022, 01, 6),
                DateTo = new DateTime(2022, 01, 06)
            },

结果应如下所示:

             new Availability
            {
                Accessibility = 1,
                RoomTypeId = "12345",
                Rate = 50,
                DateFrom = new DateTime(2022, 01, 01),
                DateTo = new DateTime(2022, 01, 02)
            },
                new Availability
            {
                Accessibility = 1,
                RoomTypeId = "12345",
                Rate = 100,
                DateFrom = new DateTime(2022, 01, 04), <- missing (2002, 01, 03) so it should crate a new group
                DateTo = new DateTime(2022, 01, 04)
            },
                new Availability
            {
                Accessibility = 6, <- different
                RoomTypeId = "12345",
                Rate = 100,
                DateFrom = new DateTime(2022, 01, 05),
                DateTo = new DateTime(2022, 01, 06)
            }

我怎样才能以最佳方式做到这一点？我尝试按 RoomTypeId 对列表进行分组，按日期排序并将日期与以前的元素进行比较，但还不是这样。

Answer 1

这有点脏，但可以提供帮助!您可以跳过不感兴趣的元素，同时保留一些标志元素。而且它只是一个枚举，所以 O(n) 复杂度

public static IEnumerable<Availability> GetMerged(List<Availability> oldList)
{
    var oldValue = oldList[0];
    foreach (var currentValue in oldList)
    {
        if (IsDifferent(oldValue, currentValue))
        {
            yield return oldValue;
            oldValue = currentValue;
        }
    }

    yield return oldValue;
}

public static bool IsDifferent(Availability x, Availability y)
{
    if (x.Accessibility != y.Accessibility || x.Rate != y.Rate || x.RoomTypeId != y.RoomTypeId)
        return true;
    if (Math.Abs((x.DateFrom - x.DateTo).TotalDays) > 1) 
        return true;

    return false;
}

您也可以通过 LINQ 组按方法和覆盖自定义比较器，但您应该选择正确的自定义 GetHashCode 函数，我发现现在很难。