Question

I know I could very easily accomplish this using loops, but I’m looking for the most efficient solution for my question.

Suppose I have 2 lists(of string):

Dim lst1 as new list(of string)
Dim lst2 as new list(of string)

And both have the same number of elements, for example:

Lst1:    Lst2:
a        abc1
a        abc2
b        abc3
a        abc4
b        abc5
c        abc6
a        abc7
c        abc8

Now, I’m looking to get, for example, all the elements from lst2 for which the corresponding elements in Lst1 = “a”

So my final result will be:

Lst3 = Items from Lst2 where corresponding Items in Lst1 = "a"
Lst3 = {abc1, abc2, abc4, abc7}

Again, I know this would be SUPER easy to do with loops, but I’m wondering how to do this via Linq.

Thanks!!!

Answer 1

List<string> Lst1 = new List<string> { "a", "a", "b", "a", "b", "c", "a", "c"};
List<string> Lst2 = new List<string> { "abc1", "abc2", "abc3", "abc4", "abc5", "abc6", "abc7", "abc8" };

var Lst3 = Lst2.Where((s, i) => Lst1[i] == "a").ToList();