Linq对'false'返回null，其中子句

Question

我有一个类似的查询：

var solution = (from hit2 in Hits.Where(x => x.Combination.Count == 2)
                where IsPossibleHit(hit2, 2, currentSymbols)
                from hit3 in Hits.Where(x => x.Combination.Count == 3)
                where IsPossibleHit(hit3, 3, currentSymbols)
                from hit4 in Hits.Where(x => x.Combination.Count == 4)
                where IsPossibleHit(hit4, 4, currentSymbols)
                from hit5 in Hits.Where(x => x.Combination.Count == 5)
                where IsPossibleHit(hit5, 5, currentSymbols)
                select new
                {
                    hitsList = new List<Hit>(){
                     hit2,
                     hit3,
                     hit4,
                     hit5}
                }).ToList();

我的问题是，在进行分组时，如果可能命中hit2和hit3，则需要创建新对象，但是因为hit4返回false，整个组合都将被丢弃。

如何实现呢？

编辑：我想我没有弄清楚我需要什么，或者我的问题是：

我的问题是，当IsPossibleHit（hitN）返回false时，整个组合都将被丢弃（由linq），但是我需要的是无论如何都创建了对象，将返回false的命中设置为null，甚至不添加新对象的命中列表。

Answer 1

var solution = (from hit2 in Hits.Where(x => x.Combination.Count == 2)
                where IsPossibleHit(hit2, 2, currentSymbols)
                let h3 = from hit3 in Hits.Where(x => x.Combination.Count == 3)
                            where IsPossibleHit(hit3, 3, currentSymbols)
                let h4 = from hit4 in Hits.Where(x => x.Combination.Count == 4)
                            where IsPossibleHit(hit4, 4, currentSymbols)
                let h5 = from hit5 in Hits.Where(x => x.Combination.Count == 5)
                            where IsPossibleHit(hit5, 5, currentSymbols)
                select new
                {
                    hitsList = new List<Hit>(){
                     hit2,
                     h3,
                     h4,
                     h5}
                }).ToList();

尝试类似的事情。 请检查语法，因为我尚未运行或编译它。

Answer 2

您想按匹配数分组，并仅在每个分组中保留可能的匹配数？ 用Where过滤，然后用GroupBy过滤：

var groupedHits = from h in Hits
                  where h.Combination.Count >= 2 && h.Combination.Count <= 5
                  where IsPossibleHit(h, h.Combination.Count, currentSymbols)
                  group h by h.Combination.Count

Answer 3

我想您想做的是：

var res = Hits.Where(h => h.Combination.Count >= 2
                       && h.Combination.Count <= 5
                       && IsPossibleHit(h, h.Combination.Count, currentSymbols)
               ).ToList();