MATLAB: Creating dumthe variables from categorical variable

Question

Suppose there is a column vector array n containing unique but repeating values of the form

1
1
5
7
7

The aim is to create a matrix D which contains in its columns dummy variables for each unique value in n of the form

1 0 0
1 0 0
0 1 0
0 0 1
0 0 1

I use the following code:

uniq = unique(n);
N_obs = size(n,1);
N_ind = size(uniq,1);
D = NaN(N_obs,N_ind);
D(:,1) = n == uniq(1,1);
D(:,2) = n == uniq(2,1);
D(:,3) = n == uniq(3,1);

This produces the desired D matrix. However, it is tedious to write the last three lines so I wanted to use a for loop of the form

for i = N_ind
    D(:,i) = n == uniq(i,1);
end

But this gives

NaN NaN 0
NaN NaN 0
NaN NaN 0
NaN NaN 1
NaN NaN 1

Where is my mistake in the loop?

Answer 1

for i = 1 : N_ind