Find the index of first and last non zero in column

I got the array as shown

I would like to extract the index (idx) of the first and last non zero in column, how can I do that.

The expected return of the code is

data(idx_first) = [1 1 2]
data(idx_last) = [1 5 5]

Answer 1

[Chunru]

x = [0 1 0 4; 1 2 0 1; 0 1 2 0; 0 0 0 0]

[m, n] = size(x);
ind = zeros(1, n);
for i=1:n
    xlast = find(x(:, i), 1, 'last');
    ind(i) = sub2ind([m n], xlast, i);
end

x(ind)

[Teerapong Poltue]

ther's a tiny problem on this code when the colum is entire 0, it caused error in sub2ind. How can I solve that?

[Chunru]

[m, n] = size(x);
ind = nan(1, n);
for i=1:n
    xlast = find(x(:, i), 1, 'last');
    if ~isempty(xlast)
        ind(i) = sub2ind([m n], xlast, i);
    end
end

y = zeros(1,n);
ind0 = ~isnan(ind);
y(ind0) = x(ind(ind0))

Answer 2

[KSSV]

A = [0 89 90 0 99 100 0] ; 
id1 = find(A,1,'first')

id1 = 2

id2 = find(A,1,'last')

id2 = 6