# How to specify positions in a matrix by an array?

If I have an array of sets of points such as

pts = {{2,4},{1,3},{5,7}}


Is there any super short command to use those pairs to output their respective elements in a matrix in one felt swoop without loops?

Also, is there a way to output elements of an array corresponding to just the first or just the second element in all pairs? so given an array

array = {1,2,3,4,5,6,7,8}


output only

{2,1,5}


corresponding to the first element in each pair in pts

• Take a look at Part, Extract, Span and friends. array[[pts[[All, 1]]]]. – Kuba Jun 17 '15 at 17:00
• @Kuba, perfect, thank you! – Raksha Jun 17 '15 at 17:11
• @Kuba ups! Haven't read your comment in time. Sorry – Dr. belisarius Jun 17 '15 at 17:25
• @belisarius I don't think you should be, why? :) – Kuba Jun 17 '15 at 17:32
• @Kuba I used Extract in my answer and you suggested that a pair of minuts before in your comment. Nothing to worry about, I guess! – Dr. belisarius Jun 17 '15 at 17:48

SeedRandom[42];