I have two vectors a and b. I want to count how many times the value '-1' appears in b corresponding to unique elements in a. Is there an efficient way to do this without loops?
a = [1,1,1,1,1,2,2,2,2,2,3,3,4,4,4,5,5,5,5,5,5]';b = [1,1,-1,1,-1,-1,-1,-1,1,1,-1,1,1,-1,-1,1,1,-1,-1,1,1]';
desired output:
1--22--33--14--25--2
Best Answer