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vb.netlinqlambdaminimum

How to select a single object using Linq in vb.net

I have done a lot of searching to what appears to be a simple LINQ problem but I can't figure out how to do grab an object out of a collection that has a specified minimum (or max value) without resorting to a sort like this:

dim customers= GetCustomers()

dim youngest = (From c in customers
                 Order By c.age Ascending).ToList.First

This (untested code) structure works fine with the exception that the entire customer array must be sorted and placed into a list for the only purpose of extracting the first value. That can't be the best way to get the minimum!

Note that I want the whole c record in this case, not the minumum age of a customer that can be done like this (a typical example):

dim customers= GetCustomers()

dim youngest = (From c in customers
                 Select c.age).Min

Or even

dim customers= GetCustomers()

dim youngest = (From c in customers
                 Select c).Min(Function(x) x.age)

I can't for the life of me figure out how to get the whole object (or even the index) without resorting to the sort...

Solution

  • Again, C# code, I'm not sure of I got it right in VB.NET

    C#

      Customer youngest = customers.Aggregate((c1, c2) => (c1.age < c2.age) ? c1 : c2);

    VB.NET

      dim youngest = customers.Aggregate( Function(ByVal c1, ByVal c2) IF( (c1.age < c2.age) , c1 , c2  ) );