使用 linq 按范围分组

Group by range using linq(使用 linq 按范围分组)

问题描述

我们如何使用分组范围等于或大于?

how can we use groupped ranges for equal or greater than ?

var data = new[] {
    new { Id = 0, Price = 2 },
    new { Id = 1, Price = 10 },
    new { Id = 2, Price = 30 },
    new { Id = 3, Price = 50 },
    new { Id = 4, Price = 120 },
    new { Id = 5, Price = 200 },
    new { Id = 6, Price = 1024 },
};

var ranges = new[] { 10, 50, 100, 500 };
var grouped = data.GroupBy( x => ranges.FirstOrDefault( r => r > x.Price ) );

grouped ouput is 
price 10-50 -> 3 
price 50-100 -> 1 
price 100-500 -> 2 

需要的输出按等于或大于使用的范围分组

Needed output is grouped by equal or greater than the range used

price >= 10 -> 6
price >= 50 -> 4
price >= 100 -> 3
price >= 500 -> 1

推荐答案

var grouped = ranges.Select(r => new { 
            Price = r, 
            Count = data.Where(x => x.Price >= r).Count() });

另一种选择(如果您有大量数据，那么分组比枚举每个价格组的所有数据更好):

And another option (if you have huge data, then grouping is better than enumerating all data for each price group):

var priceGroups = data.GroupBy(x => ranges.FirstOrDefault(r => r > x.Price))
                      .Select(g => new { Price = g.Key, Count = g.Count() })
                      .ToList();

var grouped = ranges.Select(r => new
{
    Price = r,
    Count = priceGroups.Where(g => g.Price > r || g.Price == 0).Sum(g => g.Count)
});

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