How to find where certain groups of zeros are located in a cell

https://www.mathworks.com/matlabcentral/answers/215163-counting-a-groupe-of-zeros#answer_177894

As a follow up question to this answer provided by Image Analyst - Lets say I wanted to locate the group of 4 zeros in the array, how would I go about that?

An example of my desired output is this:

I just recently used this code on a cell array of strings, x, to provide the locations of cells containing the string 'Cut A'.

x = table2cell(RS422_table(1,1));
idx = find(strcmp(x{1,1}(1,:), 'Cut A'));
idx =

  Columns 1 through 8

        3631        3632        3633        3634        3635        3636        3637        3638

  Columns 9 through 16

        3639        3640        3641        3642        3643        3644        3645        3646

  Columns 17 through 24

        3647        3648        3649        3650        3651        3652        3653        3654

  Columns 25 through 30

        3655        3656        3657        3658        3659        3660

where each entry in idx is a position of a string 'Cut A' in a group that was found.

How can I do this with groups of zeros instead?

My MATLAB Release is 2018b

Answer 1

[Amrtanshu Raj]

Hi,

Assuming you want to find the first index of all the groups of 4 zeros in a array. Here is the code -

 arr = [1 0 1 0 0 1 1 1 1 0 0 0 0 1 1 0 1 0 0 0 0 1 1 1 0 0 0 0 1 1 0 1 0]; %sample Data
 
 [lb,num] = bwlabel(arr==0); %find groups of zeros
 k = regionprops(lb,'Area'); %Find number of zeros in each group
 for i=1:num 
    if k(i).Area==4 %check the groups for which number of zeros is 4
        find(lb==i,1) %find the start index of those groups
    end
end