How to determine connectivity with binary numbers?

I am looking to optimize the material properties of a composite matrix made up of fibers and a matrix. One of the constraints are that the fibers must be connected. For example the following matrix shows fibers all connected to each other,

[1 1 2 2 2; 1 1 1 2 2; 2 1 1 1 2; 2 1 1 2 2; 2 2 2 2 2];

Where 1 is a fiber, and 2 is the matrix(epoxy) material.

Here is an example of an incorrect matrix that does not meet the constraints.

[1 2 2 2 2; 2 2 1 2 2; 2 2 2 2 1; 1 1 2 2 2; 2 2 2 2 2]; What function would be most useful to make a constraint, assuring the 1's are connected?

I tried to use the function bwlabel, but it seems to only work for "traditional" binary 0 and 1. I need to keep the numbers 1 and 2 for my problem. Is there a way to do this still?

Answer 1

[Geoff]

Yeah.

A = [1 2 2 2 2; 2 2 1 2 2; 2 2 2 2 1; 1 1 2 2 2; 2 2 2 2 2];
B = ~logical( A - 1 );

Now do your tests with B, leaving A unchanged.

[Walter Roberson]

You might find

B = (A == 1);

easier to read.

[David]

Thank you Geoff.