Question

Possible Duplicate:
randperm subset of random m-by-n matrix

When trying to randomly select 1000 rows from a dataset “fulldata” I get an error, im not very sure how its done in matlab but this is what I tryed:

data = datasample(fulldata,6,1000)

The fulldata is 490256×6 and I want to select 1000 random rows from this data. In matlab its throwing the error

??? Undefined function or method 'datasample' for input arguments
of type 'double'.

Error in ==> randomselection at 44
data = datasample(fulldata,6,1000)

Answer 1

You could instead to something like this to get it without relying on datasample:

pointsToPick = 1000;  %# Numbers to pick
rVec = randperm(N);   %# Random permutation of datapoint indices (N=490256 in your case)  

randomSample = fulldata(rVec(1:pointsToPick),:); %# Random sample