Creating a matrix of logical arrays using an exsiting matrix

given a natural number n between 1 to 10, how do you create a logical array of size 10 where the n-th index has the value 1 ?

more accurately my problem is the following :

I have a column vector Y of size 5000 with values between 1 to 10 and I want to create a matrix of size 5000x10 where the i-th row is a logical array that has all zeros except for the n-th index, corresponding to the value of Y(i).

I wish to implement this vectorized only, no loops. How do I do this ?

Answer 1

[Wan Ji]

Use eye

num_labels = 10;
Y = [1;2;3;4;3;2;4;5;3;3;5;7;8]; % example Y
E =eye(num_labels)==1;
Your_matrix = E(Y,:)

Then

Your_matrix =

  13×10 logical 数组

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

Or you can use sparse command

s = sparse(1:numel(Y),Y,true,numel(Y),num_labels);
Your_matrix = full(s)

[Tomer Marom]

Works perfectly, thank you !