Matlab giving different results sometimes as a row vector and sometimes as a column vector

Moved an entire for loop 1. outside of another for loop 2. When for loop 1 was inside, my code would sometimes giving a row vector for find instead of column vector. Happens randomly. I have sorted it out now as mentioned above but would like to know why this was happening.

[Ameer Hamza]

Can you show the code where this happen?

[Anindya Ghosh]

loop 1

for K = 1:human_count
            hr_pool = find(h_dist(:,K) <= 2);
            [hr_pool_ro, hr_pool_ho] = find(h_dist <= 2);
            h_interaction = 0; % Human to robot nodes
            if ~isempty(hr_pool)
                h_interaction = h_interaction + length(hr_pool);
                hr_int(iter,K) = h_interaction;
                obs_am = [hr_pool_ho,hr_pool_ro];
                pp{K,:} = obs_am(find(obs_am(:,1) == K)',2);
                obs{K,iter}.robots = pp{K,1}';
            elseif isempty(hr_pool)
                obs{K,iter}.robots = 0;
            end
end

loop 2

for i = 1:robot_count
end