Choose randomly rows in a matrix

Hi I have a matrix with 2 columns, the first is for 'ID', the second is for 'age'. I want to randomly pick 'n'(e.g. 2) IDs of the matrix and return the IDs and the age of the same row.

Thanks

Answer 1

[Sean de Wolski]

doc randperm

Then use the output of this as an index into your matrix.

x = magic(10);
idx = randperm(10,2)
x(idx,:)

[Vanessa]

when I write idx=randperm(10,2)

??? Error using ==> randperm Too many input arguments.

[Walter Roberson]

You are using an old version of MATLAB that does not support that syntax for randperm. Instead use

idx = randperm(size(x,1));
x(idx(1:2),:)

[Vanessa]

it works :) thanks Walter