Question

I have two matrices: matrix {a} <252×1> is a subset of matrix {b} <252×4000>. I need to determine the number of days before and after the values of matrix {a} occurred in matrix {b}.

Example:

Matrix a  Matrix b
10       12 34 54 10
23       23 98 78 98
43       98 53 43 88
44       98 44 88 78

Output
1  1  1  10
23 1  1  1
1  1  43 1
1  44 1  1

Days
3 0
0 3
2 1
1 2

Answer 1

This answer assumes there is only one match per row:

a = [10;23;43;44]
b = [12 34 45 10;23 98 78 98;98 53 43 88; 98 44 88 78]
l = bsxfun(@eq, a, b)
[c r] = find(l')
Days = [c - 1, size(b, 2) - c]
Output = b.*l + ~l

If the assumption is bad then I think you’ll be better off using loops.