MATLAB: Count number of indices

diff()indexMATLAB

I have an array with 7 columns filled with data. Column 2 has 0s then a 1 then 0s and then a -1 in repeating order. The number of 0s between a 1 and a -1 varies.
In column 2 I want to count for each cell which has the value 1, the number of cells there are until the next cell with value -1. If the count is bigger than 100, I want to add the index of the cell with value 1, to the first available cell in column 8.
I have come furthest with the following code:
n=1;
for i = 1:length(arrayA)
    if arrayA(i,2) == 1
        if abs(find(arrayA(i,2)==1) - find(arrayA(:,2)==-1)) > 200
            arrayA(n,8)=i;
            n=n+1;
        end
    end
end
yet column 8 still doesn't have any values when I run the whole thing.
Pretty sure the problem is line 3 but have no more ideas left on how I could make it work…

Best Answer

n=1;
I=find(arrayA(:,2)==1);
J=find(arrayA(:,2)==-1);
for k=1:length(I)
    if J(k)-I(k)>100
        arrayA(n,8)=pos_one(k);
        arrayA(n,9)=neg_one(k); 
        n=n+1;
    end
end
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