How can I use nested loops to pair one piece of data with multiple other pieces?

I am currently struggling with the following problem involving looping and pairing data.

I have a table of routes between different regions. Each route is only between a specific region and another specific region. In each region, there are multiple locations. So there are x locations in region A and y locations in region B. I need to pair each location in region A with each location in region B for each route. I know this requires some nested loops, but I am getting lost on how I can properly pair this data.

The problem arises in that there might not be the same number of locations in region A and region B. I'm having trouble looping through this correctly to make sure each location in region A is paired with each location in region B.

To visualize this:

Route 1 has Region A and Region B.

Region A has the following locations: A1, A2, A3.

Region B has the following locations: B1, B2, B3, B4, B5.

I need to essentially have a final result of this:

(A1 -> B1) (A1 -> B2) (A1 -> B3) (A1 -> B4) (A1 -> B5)

(A2 -> B1) (A2 -> B2) (A2 -> B3) (A2 -> B4) (A2 -> B5)

(A3 -> B1) (A3 -> B2) (A3 -> B3) (A3 -> B4) (A3 -> B5)

Does anyone know an efficient way of completing this? Thank you in advance for the help!

Answer 1

[KSSV]

a = rand(1,3) ; 
b = rand(1,5) ;

[B,A] = meshgrid(b,a) 

[sid28]

Thank you for the answer. I'm still a little confused on how I can use this to pair the pieces of data. This seems to only create the grids but does not actually help with combining the data.

[KSSV]

[A(1,:);B(1,:)]'

Give you the first pair ..and so on..

[Stephen23]

"I need to essentially have a final result of this:"

[A,B] = ndgrid(1:3,1:5);
M = repelem(A,1,2);
M(:,2:2:end) = B;
compose("(A%d -> B%d)",M)

ans = 3×5 string array
    "(A1 -> B1)"    "(A1 -> B2)"    "(A1 -> B3)"    "(A1 -> B4)"    "(A1 -> B5)"
    "(A2 -> B1)"    "(A2 -> B2)"    "(A2 -> B3)"    "(A2 -> B4)"    "(A2 -> B5)"
    "(A3 -> B1)"    "(A3 -> B2)"    "(A3 -> B3)"    "(A3 -> B4)"    "(A3 -> B5)"

% (A1 -> B1) (A1 -> B2) (A1 -> B3) (A1 -> B4) (A1 -> B5)
% (A2 -> B1) (A2 -> B2) (A2 -> B3) (A2 -> B4) (A2 -> B5)
% (A3 -> B1) (A3 -> B2) (A3 -> B3) (A3 -> B4) (A3 -> B5)