Beispiel #1
0
 public static IEnumerable <Bird> Search(this IEnumerable <Bird> source, BirdSearch search)
 {
     return(source
            .Where(s => string.IsNullOrEmpty(search.CommonName) || s.CommonName.Contains(search.CommonName))
            .Where(s => string.IsNullOrEmpty(search.Country) || s.Habitats.Any(h => h.Country.Contains(search.Country)))
            .Where(s => search.Colors.Any(c => s.PrimaryColor.Equals(c) || s.SecondaryColor.Equals(c)) ||
                   search.Colors.Join(s.TertiaryColors, sc => sc, tc => tc, (sc, tc) => sc).Any())
            .Skip(search.Page * search.PageSize)
            .Take(search.PageSize));
 }
        static void TestBirds()
        {
            var birds              = BirdRepository.LoadBirds();
            var sightings          = birds.SelectMany(b => b.Sightings);
            var avgS               = birds.Select(b => b.Sightings.Count()).Average();
            var sightingsByCountry = sightings
                                     .GroupBy(s => s.Place.Country)
                                     .Select(g => new { Country = g.Key, Sightings = g.Count() });
            var birdCountByStatus = birds
                                    .Where(b => b.ConservationStatus != "LeastConcern" && b.ConservationStatus != "NearThreatened")
                                    .GroupBy(b => b.ConservationStatus)
                                    .Select(selector: g => new { Status = g.Key, Count = g.Count(), Sightings = g.Sum(b => b.Sightings.Count) });
            var statuses = birds
                           .Select(b => b.ConservationStatus)
                           .Where(s => s != "LeastConcern" && s != "NearThreatened")
                           .Distinct();
            var endangeredSightings = birds
                                      .Join(statuses, b => b.ConservationStatus, s => s, (b, s) => new { Status = s, Sigthings = b.Sightings })
                                      .GroupBy(a => a.Status)
                                      .Select(g => new { Status = g.Key, Sightings = g.Sum(selector: s => s.Sigthings.Count) });

            var importedBirds = BirdRepository.LoadImportedBirds();
            var matchingBirds = birds.Intersect(importedBirds, new BirdComparer());
            // Perform outer join to get elements that exist in one enumerable and not in the other
            var newBirds = importedBirds.GroupJoin(birds,
                                                   ib => ib.CommonName,
                                                   b => b.CommonName,
                                                   (ib, b) => new { ImportedBird = ib, Birds = b })
                           // Variant 1: flatten the grouping first, providing default value for elements with no matches, then filter records
                           //.SelectMany(gb => gb.Birds.DefaultIfEmpty(), (gb, b) => new { ImportedBird = gb.ImportedBird, Bird = b })
                           //.Where(a => a.Bird == null)

                           // Variant 2: filter the grouping directly - my option
                           .Where(a => a.Birds.Count() == 0)

                           .Select(a => a.ImportedBird)
                           .ToList();

            var searchParams = new BirdSearch
            {
                Country = "United States",
                Colors  = new List <string> {
                    "White", "Brown", "Black"
                },
                Page     = 0,
                PageSize = 5
            };
            var foundBirds = birds.Search(searchParams);
        }