grabbing specific rows from matrix

I have the following 25 x 3 matrix (let's call first column X, second Y, third INDEX)

xy_index =

1 1 1

2 1 2

3 1 3

4 1 4

5 1 5

1 2 6

2 2 7

3 2 8

4 2 9

5 2 10

1 3 11

2 3 12

3 3 13

4 3 14

5 3 15

1 4 16

2 4 17

3 4 18

4 4 19

5 4 20

1 5 21

2 5 22

3 5 23

4 5 24

5 5 25

I want to extract rows (and so X,Y and INDEX) corresponding to INDEX [1 5 13 21 25] (as an array). Result shoud be

extracted_xy_index =

1 1 1

5 1 5

3 3 13

1 5 21

5 5 25

Thanks!

Answer 1

[Fangjun Jiang]

RowSelection=[1 5 13 21 25];

xy_index(RowSelection ,:)

[giuseppe insignito]

easy! thanks

Answer 2

[David Hill]

idx=ismember(xy_index(:,3),index);
extracted_xy_index=xy_index(idx,:);