无法使用group-by访问字段，也无法使用linq访问多个联接

我只想列出那些记录中有差异的具有平均值的类别。

这种差异存在于两个表中：TestOperation，TestOperationDifference

我想计算以下3个字段的平均值：

TestOperation:DiffPerc
If DiffPerc  < 100 
    "Difference is there and take value of DiffPerc to calculate average"
else 
    "Dont take that record"

TestOperationDifference:DiffPerc,DiffRec
If DiffPerc  < 100 
    "Difference is there and take value of DiffPerc and DiffRec to calculate average"
else 
    "Dont take that record"


finalAverage=(
                   Average(TestOperation.DiffPerc) 
                    + Average(TestOperationDifference.DiffPerc)
                    + Average(TestOperationDifference.DiffRec)
              )/3

输出如下：

[0]=Mobile 
    Electronics
    FinalAverage=30.00
[1]=Shoes 
    Sports
    FinalAverage=70.00
.
.
.

我的代码：

public class Category
        {
            public int Id { get; set; }
            public string Name { get; set; }
            public Nullable<int> ParentId { get; set; }
            public virtual ICollection<Variants> Variants { get; set; }
        }
  public class Variants
        {
            public int Id { get; set; }
            public string Name { get; set; }
            public string Type { get; set; }
            public int CategoryId { get; set; }
            public virtual ICollection<SubVariants> SubVariants { get; set; }
            public virtual Category Category { get; set; }
        }
        public class SubVariants
        {
            public int Id { get; set; }
            public int VariantId { get; set; }
            public string Name { get; set; }
            public virtual Variants Variants { get; set; }
            public virtual ICollection<TestOperationDifference> TestOperationDifference { get; set; }
            public virtual ICollection<TestOperationDifference> TestOperationDifference1 { get; set; }
            public virtual ICollection<TestOperation> TestOperation { get; set; }
            public virtual ICollection<TestOperation> TestOperation1 { get; set; }
        }
        public class Test
        {
            public int Id { get; set; }
            public string Version { get; set; }
            public virtual ICollection<TestOperation> TestOperation { get; set; }
            public virtual ICollection<TestOperationDifference> TestOperationDifference { get; set; }
        }
        public class TestOperation
        {
            public int Id { get; set; }
            public Nullable<int> TestId { get; set; }
            public int SourceSubVariantId { get; set; }
            public int TargetSubVariantId { get; set; }
            public decimal DiffPerc { get; set; }
            public virtual SubVariants SubVariants { get; set; }
            public virtual SubVariants SubVariants1 { get; set; }
            public virtual Test Test { get; set; }
        }
        public class TestOperationDifference
        {
            public int Id { get; set; }
            public Nullable<int> TestId { get; set; }
            public int SourceSubVariantId { get; set; }
            public int TargetSubVariantId { get; set; }
            public decimal DiffPerc { get; set; }
            public decimal DiffRec { get; set; }
            public virtual SubVariants SubVariants { get; set; }
            public virtual SubVariants SubVariants1 { get; set; }
            public virtual Test Test { get; set; }
        }

我的查询：

 var query = from cat in context.Category
             join v in context.Variants on cat.Id equals v.CategoryId
             join sv in context.SubVariants on v.Id equals sv.VariantId
             join to in context.TestOperation on sv.Id equals to.SourceSubVariantId
join tod in context.TestOperationDifference on sv.Id equals tod.SourceSubVariantId
             where 
              (to.DiffPerc < 100) 
                 ||
              (tod.DiffPerc < 100 )
               group cat by new {catid = cat.Id} into grp 
              select new 
              {
                subcategoryname=grp. //not getting property here                 
                ParentCategoryName=grp.
                FinalAverage=    
              }

但在上面的查询中，当我试图访问子类别名称时我无法访问它。

演示Fiddle

 var query = (from cat in category
                         join v in variants on cat.Id equals v.CategoryId
                         join sv in subVariants on v.Id equals sv.VariantId
                         into grp
                         select new { id = cat.Id, subvariant = v.SubVariants, name = cat.Name, type = v.Type})
                         .GroupBy(x => new {id = x.id, subvariant = x.subvariant});