C＃Linq如何枚举两个日期之间的时间段以获取图表的数据(C# Linq How to enumerate over time periods between two dates to get data for a graph)

 我有一个在某些日期发生的事件表，知道我想格式化数据，以便能够绘制事件的线图随着时间的推移。 数据的标签是x轴上的值，数据是y轴上的值。 
 
 数据应该在两个日期之间，在这个例子中它是from和to，然后它必须是几天的时间间隔 
 
 这是我的第一次尝试。 
 
var graphData = bookings.Where(x => x.DateCreated > from && x.DateCreated < to)
                        .GroupBy(x => new { x.DateCreated.Year, x.DateCreated.Month, x.DateCreated.Day })
                        .OrderBy(x => x.Key.Year).ThenBy(x => x.Key.Month).ThenBy(x => x.Key.Day)
                        .Select(x => new GraphData
                        {
                            Label = x.Key.Day + "/" + x.Key.Month + "/" + x.Key.Year,
                            Data = x.Count()
                        }).ToList();
 
 这为我提供了正确的数据图， 但仅限于创建任何事件的日期。 
 
 我希望在我的图表中包含未发生任何事件的日期的数据，以便我可以在同一图表上比较不同类型的事件。 
 
 我想出了这个解决方案 
 
var dateRanges = Enumerable.Range(0, 1 + to.Value
                           .Subtract(from.Value).Days)
                           .Select(offset => from.Value.AddDays(offset)).ToList();
var graphData = dateRanges.Select(day => new GraphData()
                {
                   Label = day.ToString("D"),
                   Data = bookings.Count(x => x.DateCreated.Date == day.Date)
                }).ToList();
 
 这似乎是非常低效的。 
 
 是否有任何方法可以使用linq查询执行此操作，以便我不必对每个日期进行计数？ 

I have a table of events that occur on certain dates, know i want to format the data to be able to draw a line graph of events over time. The data has a label which is the value on the x axis and data which is the value on the y axis.
 
The data should be between two dates, in this example its from and to and then it must be in time intervals of days
 
This was my first attempt.
 
var graphData = bookings.Where(x => x.DateCreated > from && x.DateCreated < to)
                        .GroupBy(x => new { x.DateCreated.Year, x.DateCreated.Month, x.DateCreated.Day })
                        .OrderBy(x => x.Key.Year).ThenBy(x => x.Key.Month).ThenBy(x => x.Key.Day)
                        .Select(x => new GraphData
                        {
                            Label = x.Key.Day + "/" + x.Key.Month + "/" + x.Key.Year,
                            Data = x.Count()
                        }).ToList();
 
This give the correct data for me to graph but only for the days which there where any events created.
 
I want to have the data for the days where nothing happened included in my graph so i can compare different kinds of events on the same graph.
 
I came up with this solution 
 
var dateRanges = Enumerable.Range(0, 1 + to.Value
                           .Subtract(from.Value).Days)
                           .Select(offset => from.Value.AddDays(offset)).ToList();
var graphData = dateRanges.Select(day => new GraphData()
                {
                   Label = day.ToString("D"),
                   Data = bookings.Count(x => x.DateCreated.Date == day.Date)
                }).ToList();
 
It seems to be very inefficient. 
 
Is there any way to do this with a linq query so that i don't have to do a count on each date?

原文：https://stackoverflow.com/questions/42276647