filtering a list using LINQ

Question

i have a list of project objects:

IEnumerable projects

a Project class as a property called Tags

Answer 1

We should have the projects which include (at least) all the filtered tags, or said in a different way, exclude the ones which doesn't include all those filtered tags. So we can use Linq Except to get those tags which are not included. Then we can use Count() == 0 to have only those which excluded no tags:

var res = projects.Where(p => filteredTags.Except(p.Tags).Count() == 0);

Or we can make it slightly faster with by replacing Count() == 0 with !Any():

var res = projects.Where(p => !filteredTags.Except(p.Tags).Any());