replacing ascending numbers with continous numbers

Hello everybody,

I am looking for a fast and efficient way to convert a vector of non continous ascending numbers to continous numbers.

As an example:

The vector

[4 20 35 22 10 49]

should become

[1 3 5 4 2 6]

at the moment I'm using a for loop, look for the lowest number write the runtime index into the result vector and set the position in the original vector to an illegal value. I know this is not the best way but it was the only one I could think of.

Also I'm not doing a single vector at a time but doing this to the columns of a matrix.

Thank you

Answer 1

[Amit]

A = [4 20 35 22 10 49];
B = 1:numel(A);
[~,C] = sort(A);
B(C) = B; % Your vector

[Daniel]

Thank you! Do you happen to know a way to extend this to a matrix? I.e. do this to every column of a matrix at once.

[Amit]

% Your matrix is named A
[m,n] = size(A);
B = 1:m;
[~,C] = sort(A);
D = zeros(m,n);

for i = 1:n
  D(C(:,i),i) = B;
end

[Daniel]

Mile grazie! Thank you very much. This is way more elegant than anything I managed to butchered.