Find an outline to the valued data in a matrix of zeros and values

Hello,

I have matrix of data points that I basically need to distinguish a boundary between the numbers above zero and the zero.

for example-

0 2 2 0 0 0

0 0 2 1 2 0

0 2 1 1 2 0

0 0 2 1 2 0

Where I want to draw a line along all of the 2s (note these values are not the same in the actual matrix so I can't just say where x=2).

The end goal would be to say anything to the right of the right line is NaN, anything to the left of the left line is also NaN, leaving only the middle values intact.

usually I would just turn zero to NaN and create a mask that way, but there are some zeros in the center of the matrix that I do still need.

I might be going about it wrong and there is likely a very simple solution which I have over complicated in my head.

I am not asking for a full code, just maybe some ideas and helpful functions that could do this.

Thank you!

Answer 1

[KSSV]

REad about bwlabel.

I = [0 2 2 0 0 0
0 0 2 1 2 0 
0 2 1 1 2 0
0 0 2 1 2 0];
L = bwlabel(I)

L = 4×6

0 1 1 0 0 0 0 0 1 1 1 0 0 1 1 1 1 0 0 0 1 1 1 0

[H]

Thank you, this helps, do you have any thoughts on how I could then do an outline of the 1s that are next to zero e.g down the 1s-

0 1 1 0 0 0

0 0 1 0 1 0

0 1 0 0 1 0

0 0 1 0 1 0

No worries if not!

[H]

Or perhaps just anything to the left or right of the mask is NaN would probably work well. Thank you!

[KSSV]

r1 = [0     1     1     0     0     0] ;
% 
strfind(r1,[0 1])
strfind(r1,[1 0])
% Or 
find(diff(r1) == 1)
find(diff(r1) == -1)

[H]

Thank you, this helps until I have zeros in the middle of my 1's in the matrix-

0 1 1 0 0 0

0 0 1 1 1 0

0 1 1 0 1 0

0 0 1 1 1 0

I will need to find a way to only include those on the most left/right side of the matrix. Thank you for your help.