How to count number of only those zeros which are lying between 2 one's in a very simplified way in the given matrix?

a = [0, 0, 0, 0, 1, 1, 1, 1, 0, 0 ,0 ,0 ,0 ,0 ,0 ,1 ,1, 1, 1 ,0 ,0 ,0 ,1 ,0 ,0 ,1 ,1 ,1 ,1 ,1 ,0, 0, 1, 1, 1, 1, 1, 0, 0,];

[Matt J]

Why have you rebooted the same question you got 5 answers for here:

https://www.mathworks.com/matlabcentral/answers/1987778-i-have-a-matrix-i-want-to-count-number-of-only-those-zeros-which-are-lying-between-2-sets-of-consec?s_tid=srchtitle

Answer 1

[Image Analyst]

Here is one way:

a = [0, 0, 0, 0, 1, 1, 1, 1, 0, 0 ,0 ,0 ,0 ,0 ,0 ,1 ,1, 1, 1 ,0 ,0 ,0 ,1 ,0 ,0 ,1 ,1 ,1 ,1 ,1 ,0, 0, 1, 1, 1, 1, 1, 0, 0,];
% Set leading 0's to 1 since they are not between 1's
index = find(a, 1, 'first');
a(1:index) = 1;
% Set trailing 0's to 1 since they are not between 1's
index = find(a, 1, 'last');
a(index : end) = 1;
% All the rest of the 0's are between 1's so 
% count them with nnz
numZeros = nnz(a == 0)

numZeros = 14

Is that what you mean?

Answer 2

[DGM]

This uses image processing tools. This is probably more expensive, but it's another idea.

a = [0, 0, 0, 0, 1, 1, 1, 1, 0, 0 ,0 ,0 ,0 ,0 ,0 ,1 ,1, 1, 1 ,0 ,0 ,0 ,1 ,0 ,0 ,1 ,1 ,1 ,1 ,1 ,0, 0, 1, 1, 1, 1, 1, 0, 0];

% invert and pad the array so that we're selecting zeros
% and the interior zero blocks are not on the array edge
b = padarray(~a,[1 0],0,'both');
% get rid of blocks that are on the array edge
b = imclearborder(b);

% count the remaining zeros
numzeros = nnz(b(2,:))

numzeros = 14