ToDictionary is the way to go. It does work – you were just using it incorrectly, presumably. Try this: dic = dic.Where(p => p.Key == 1) .ToDictionary(p => p.Key, p => p.Value); Having said that, I assume you really want a different Where filter, as your current one will only ever find one key…
Where is the Find method on IEnumerable<T>? (Rhetorical question.) The Where and FirstOrDefault methods are applicable against multiple kinds of sequences, including List<T>, T[], Collection<T>, etc. Any sequence that implements IEnumerable<T> can use these methods. Find is available only for the List<T>. Methods that are generally more applicable, are then more reusable and have a … Read more
LINQ to entities: Video walkthroughs Channel 9 video Entity framework FAQ Entity framework performance I’ve got a lot more I tagged on Delicious.com.
This will loop through only once. Item biggest = items.Aggregate((i1,i2) => i1.ID > i2.ID ? i1 : i2); Thanks Nick – Here’s the proof class Program { static void Main(string[] args) { IEnumerable<Item> items1 = new List<Item>() { new Item(){ ClientID = 1, ID = 1}, new Item(){ ClientID = 2, ID = 2}, new … Read more
Let doesn’t have its own operation; it piggy-backs off of Select. You can see this if you use “reflector” to pull apart an existing dll. it will be something like: var result = names .Select(animalName => new { nameLength = animalName.Length, animalName}) .Where(x=>x.nameLength > 3) .OrderBy(x=>x.nameLength) .Select(x=>x.animalName);
Your status-codes are also a collection, so use Contains: var allowedStatus = new[]{ “A”, “B”, “C” }; var filteredOrders = orders.Order.Where(o => allowedStatus.Contains(o.StatusCode)); or in query syntax: var filteredOrders = from order in orders.Order where allowedStatus.Contains(order.StatusCode) select order;
This can be done as list.Sort( (emp1,emp2)=>emp1.FirstName.CompareTo(emp2.FirstName) ); The .NET framework is casting the lambda (emp1,emp2)=>int as a Comparer<Employee>. This has the advantage of being strongly typed. If you need the descending/reverse order invert the parameters. list.Sort( (emp1,emp2)=>emp2.FirstName.CompareTo(emp1.FirstName) );
var distinctItems = items.GroupBy(x => x.Id).Select(y => y.First());
Just stumbled into this oldie… To do this without the dynamic LINQ library, you just need the code as below. This covers most common scenarios including nested properties. To get it working with IEnumerable<T> you could add some wrapper methods that go via AsQueryable – but the code below is the core Expression logic needed. … Read more