How to identify the repeated elements in an array and delete those rows?

I have a matrix array like this:

1 100

2 200

3 200

4 200

5 500

And I want to identify the repeated elements on the right column, and delete the entire row of the matrix, to get something like this:

1 100

2 200

5 500

How can I do that?

Answer 1

[the cyclist]

Here is one way:

M = [1 100;
     2 200;
     3 200;
     4 200;   
     5 500];

[~,j] = unique(M(:,2));
out = M(j,:)

out = 3×2

1 100 2 200 5 500

Answer 2

[Star Strider]

Use unique —

A = [1   100
     2   200         
     3   200
     4   200   
     5   500];

[Au,ix] = unique(A(:,2),'stable');
Anew = A(ix,:)

Anew = 3×2

1 100 2 200 5 500

.