How can i create a sequence where the symbols have different probabilities?

Hello ,

I have 4 symbols 0,1,2,3 . How can i create a sequence with these symbols where every symbol should have each own probabilty .For example i want the symbols 1,2 to appear with probability q , but in the other hand the symbols 1,4 to appear with probability (1-q)/2.

In my last excersice i was asked to create a sequence where these symbols have the same probability 1/4 so i wrote the code below:

C = floor(rand(1,n)*4);

But i am little confused about this issue .Any help would be valuable.

[Walter Roberson]

hint:

probabilities 0.1, 0.23, 0.6, 0.07

random number < 0.1 is the first symbol

random number between 0.1 and 0.1+0.23 is the second symbol

random number between 0.1+0.23 and 0.1+0.23+0.6 is the third symbol...

Answer 1

[Apoorv Singh]

Walter has suggested a nice method. You basically partition the range [0:1] into partitions proportional to the probabilities. As calling rand outputs a decimal in the range [0:1] with equal probability, your problem will be solved.