How to get all possible combinations of three independent data sets?

Hello All,

I have the following problem:

I have three independent data sets of x- and y- coordinates, let them be as follows for now:

Data set 1:

A = [A_x A_y];

B = [B_x B_y];

C = [C_x C_y];

Data set 2:

D= [D_x D_y];

E = [E_x E_y];

F = [F_x F_y];

G = [G_x G_y];

Data set 3:

H = [H_x H_y];

I = [I_x I_y];

J = [J_x J_y];

I want to generate all possible combinations with a length of 3, but there can only be one for each data set:

For example:

ADJ is ok (consits of three points in three different data sets)

BEG is not ok (because E and G are in data set 2)

P.S. The real data sets consists of 30+ coordinates

Thanks you very much in advance!

Answer 1

[Walter Roberson]

A = [A_x A_y];
B = [B_x B_y];
C = [C_x C_y];

ABC = [A;B;C];

D= [D_x D_y];
E = [E_x E_y];
F = [F_x F_y];
DEF = [D;E;F];

G = [G_x G_y];
H = [H_x H_y];
I = [I_x I_y];
J = [J_x J_y];
GHIJ = [G;H;I;J];

[g1, g2, g3] = ndgrid(1:size(ABC,1), 1:size(DEF,1), 1:size(GHIJ,1));
g123 = [g1(:),g2(:), g3(:)];

all_combs = [ABC(g123(:,1),:),DEF(g123(:,2),:),GHIJ(g123(:,3),:)];

The g* variables are indices. Generate all combinations of indices using ndgrid(), and then use the indices to index into the respective dataset.

[Aris van Houten]

Thanks a lot Walter!

You are a 'MVP' for a reason. :)