How do I select items from an array using an array of indices with Linq?

Question

Following code works:

String[] A = new String[] { "one", "two", "three", "four" };
int[] idxs = new int[] { 1, 3 };
String[] B = new String[idxs.Length];
for (int i = 0; i < idxs.Length; i++)
{
     B[i] = A[idxs[i]];
}
System.Diagnostics.Debug.WriteLine(String.Join(", ", B));

output:

        two, four

Is there a LINQ way (or other one-liner) to get rid of the for loop?

Why do you want to get rid of the for loop? Is it slow? Hard to read? — Chris Gessler
– Chris Gessler, Commented Mar 20, 2013 at 12:29

Daniel Hilgarth · Accepted Answer · 2013-03-20 12:32:01Z

16

A LINQ way would be this:

var b = idxs.Select(x => A[x]).ToArray();

answered Mar 20, 2013 at 12:32

Daniel Hilgarth

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Comments

Soner Gönül · Accepted Answer · 2013-03-20 12:45:36Z

9

You can use it with Select your index and your A[index] Like:

String[] A = new String[] { "one", "two", "three", "four" };
int[] idxs = new int[] { 1, 3 };
var result = idxs.Select(i => A[i]).ToArray();

foreach(var s in result)
  Console.WriteLine(s);

Output will be:

two
four

Here is a DEMO.

edited Mar 20, 2013 at 12:45

answered Mar 20, 2013 at 12:34

Soner Gönül

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