Task

Select certain elements from an Array into a new Array in a generic way.



To demonstrate, select all even numbers from an Array.

As an option, give a second solution which filters destructively,
by modifying the original Array rather than creating a new Array.




mata
a=2,9,4,7,5,3,6,1,8
 
// Select even elements of a
select(a,mod(a,2):==0)
 
// Select the indices of even elements of a
selectindex(mod(a,2):==0)
end