How to extract first non-zero element in each column and put into a new array

I have an array which represents a 2-D vertical slice of a cloud. I want to get cloud-top properties for the cloud so I want to just plot a line graph of the top layer. But the row corresponding to the first non-zero number changes with each column. Does anyone know how I can extract the first non-zero element in each column and put that into a new array? For example:

in=[0 0 6 0 0 5;
    1 3 5 1 0 4; 
    4 4 5 3 4 5]

out=[1 3 6 1 4 5]

Answer 1

[Andrei Bobrov]

out = in(cumsum(cumsum(in~=0)) == 1)'

Answer 2

[the cyclist]

Here is a one way:

in=[0 0 6 0 0 5;
    1 3 5 1 0 4; 
    4 4 5 3 4 5];

[m,n] = size(in);

[i,j] = find(in);

[~,jj] = unique(j);

out = in(i(jj)+(0:m:(m*(n-1)))')'

Answer 3

[the cyclist]

Here is one way:

in=[0 0 6 0 0 5;
    1 3 5 1 0 4; 
    4 4 5 3 4 5];

mid = in;

for nr = size(in,1)-1:-1:1
    mid(nr,mid(nr,:)==0) = mid(nr+1,mid(nr,:)==0);
end

out = mid(1,:);

Answer 4

[the cyclist]

Here is one way:

in=[0 0 6 0 0 5;
    1 3 5 1 0 4; 
    4 4 5 3 4 5];

[m,n] = size(in);
out = nan(1,n);

for nc = 1:n
    [~,~,out(nc)] = find(in(:,nc),1);
end