我有一个类别表：
Catid | Desciption 1 | Color 2 | Size 3 | Material
和一个类别项目表
Catid | Name 1 | Red 1 | Blue 1 | Green 2 | Small 2 | Med 2 l Large 3 | Cotton 3 | Silk
Red Small Cotton Red Small Silk Red Med Cotton Red Med Silk Red Large Cotton Red Large Silk Blue Small Cotton Blue Small Silk Blue Med Cotton Blue Med Silk Blue Large Cotton Blue Large Silk Green Small Cotton Green Small Silk Green Med Cotton Green Med Silk Green Large Cotton Green Large Silk
请注意：可能有更多或更少的类别.这不是预先确定的.
有什么建议？
谢谢
解决方法
var result = list.GroupBy(t => t.Id).CartesianProduct();
使用Eric Lippert’s Blog CartesianProduct Extension Method：
static IEnumerable<IEnumerable<T>> CartesianProduct<T>(
this IEnumerable<IEnumerable<T>> sequences)
{
IEnumerable<IEnumerable<T>> emptyProduct = new[] { Enumerable.Empty<T>() };
return sequences.Aggregate(
emptyProduct,(accumulator,sequence) =>
from accseq in accumulator
from item in sequence
select accseq.Concat(new[] {item}));
}
例：
var list = new[]
{
new { Id = 1,Description = "Red" },new { Id = 1,Description = "Blue" },Description = "Green" },new { Id = 2,Description = "Small" },Description = "Med" },Description = "Large" },new { Id = 3,Description = "Cotton" },Description = "Silk" },};
var result = list.GroupBy(t => t.Id).CartesianProduct();
foreach (var item in result)
{
Console.WriteLine(string.Join(" ",item.Select(x => x.Description)));
}
输出：
Red Small Cotton Red Small Silk Red Med Cotton Red Med Silk Red Large Cotton Red Large Silk Blue Small Cotton Blue Small Silk Blue Med Cotton Blue Med Silk Blue Large Cotton Blue Large Silk Green Small Cotton Green Small Silk Green Med Cotton Green Med Silk Green Large Cotton Green Large Silk
