random selection

I have a matrix size of 96x249.How can i select 48 rows randomly and store it into a new matrix of 48x249.I have values in matrix as decimal numbers.

Answer 1

[Walter Roberson]

T = randperm(96);
NewMatrix = OldMatrix(T(1:48),:);

[Abhiya]

thanks for the answer.do i have an option to store the rest of the matrix after random selection?

[Walter Roberson]

RestOfMatrix = OldMatrix(T(49:end),:);

Answer 2

[Peter Perkins]

There are a number of ways to do this, including Walter's suggestion. But in addition, if you have access to MATLAB R2011b, there is the slightly simpler

NewMatrix = OldMatrix(randperm(96,48),:);

and if you have access to the Statistics Toolbox in R2011b, there is also

NewMatrix = datasample(OldMatrix,48);

The latter option also allows you to sample with weights, and with replacement. Of course, neither allows you to get the rest of the matrix.

Answer 3

[Abhiya]

My heartful thanks to everybody