Say I have the following:
class Widget1{
public int TypeID { get; set; }
public string Color { get; set; }
}
class Widget2
{
public int TypeID { get; set; }
public string Brand { get; set; }
}
private void test()
{
List<Widget1> widgets1 = new List<Widget1>();
List<Widget2> widgets2 = new List<Widget2>();
List<Widget1> widgets1_in_widgets2 = new List<Widget1>();
//some code here to populate widgets1 and widgets2
foreach (Widget1 w1 in widgets1)
{
foreach (Widget2 w2 in widgets2)
{
if (w1.TypeID == w2.TypeID)
{
widgets1_in_widgets2.Add(w1);
}
}
}
}
I am using two foreach loops to compare the lists by TypeID to populate a third list. Is there any other way using LINQ to compare these two lists via the TypeID? Perhaps using Interstect or some other function?
What you want here is a Join
.
var widgets1_in_widgets2 = from first in widgest1
join second in widgets2
on first.TypeID equals second.TypeID
select first;
Intersect
can be more or less thought of as a special case of Join
where the two sequences are of the same type, and can thus be applied for equality instead of needing a projection for each type to generate a key to compare. Given your case, Intersect
isn't an option.
If a particular ID is duplicated in your second set and you don't want the item to be duplicated in the results then you can use a GroupJoin
instead of a Join
:
var widgets1_in_widgets2 = from first in widgest1
join second in widgets2
on first.TypeID equals second.TypeID
into matches
where matches.Any()
select first;