Generate a loop vector with certain probability?

Hi, I have this loop to generate a matrix of size d with the numbers 1,2,3,4 according to a certain frequency (fn...) and each time one of the elements of the matrix is generated the frequency is recalculated but only after all the numbers generated in each g{x} has been completed. So actually the recalculated frequency is not completely accurate, can be a different way to calculate it not for the whole set but after each number is generated?

d= poissrnd(lambda,1,1000);

for x = 1:numel(d)

tot= q1 + q2 + q3 + q4

f1= q1 / tot

f2= q1 / tot

f3= q1 / tot

f4= q1 / tot

g{x} = randsrc(1,d(x),[1,2,3,4;f1,f2,f3,f4]);

f1 = f1 - (sum(d{x}==1));

f2 = f2 - (sum(d{x}==2));

f3 = f3 - (sum(d{x}==3));

f4 = f4 - (sum(d{x}==4));

end