如何将列表分组 <int> 并返回一个列表 <int>

Question

I have a list of ints. I want to group the list and create a new list that contains only the grouped by number that meets a certain condition. this is what i have so far. the declarating for membersList is List

int rows = 5;

List<int> memberKeys = memberKeysList
  .GroupBy(x => x)
  .Where(x => x.Count() == rows)
  .ToList();

Its complaining about converting from groupedby list to a list.

Answer 1

You need to Select the Key to get the number like:

List<int> memberKeys = memberKeysList.GroupBy(x => x)
                           .Where(x => x.Count() == rows)
                           .Select(grp => grp.Key)
                           .ToList();

If you are not going to explicitly select they Key (or the number) , then the result of GroupBy clause would be IEnumerable<IGrouping<TKey, TElement>>