#!/usr/bin/gawk -f
BEGIN  { 
	Trainf="train.arff"; Testf="test.arff"; 
	Tests = 5;
} 

/^[ \t]*$/  { next }

/@relation/ {
	Seed ? srand(Seed) : srand(1)      
	printf "">Trainf;  
	printf "">Testf }
	/@relation/,/@data/ { print $0 >> Trainf;  print $0 >> Testf; next }

{ Line[rand()] = $0  }

END { 
	for(I in Line) {
		What = (Tests-- > 0) ? Testf : Trainf;
		print Line[I]>>What;
	}
}