[R] Generate N random numbers with a given probability and condition

[Nelly Reduan]

Thank you very much for your reply.


By omitting the probability, the expected results could be:


c(2, 0, 0, 0, 0, 0, 1, 0, 5, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0)


c(0, 0, 1, 0, 0, 1, 1, 0, 6, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0)


If I omit the probability, I would like to generate N random positive integers that sum to M and the integers would be selected from a uniform distribution.


Many thanks for your time

Nell


________________________________
De : Rolf Turner <r.turner using auckland.ac.nz>
Envoyé : mercredi 4 juillet 2018 16:11:11
À : Nelly Reduan
Cc : r-help using r-project.org
Objet : Re: [R] Generate N random numbers with a given probability and condition


On 05/07/18 10:21, Nelly Reduan wrote:

> Dear all,
>
> I would like to generate N random numbers with a given probability and condition but I'm not sure how to do this.
> For example, I have N = 20 and the vector from which to choose is seq(0, 10, 1). I have tested:
>
> x <- sample(seq(0, 10, 1), 20, replace=TRUE, prob=rep(0.28, times=length(seq(0, 10, 1))))
>
> But I don�t know how to put the condition sum(x) <= max(seq(0, 10, 1)).
> Many thanks for your time.

Your thinking requires considerable clarification.

(1) Note that seq(0,10,1) is just 0, 1, 2, ..., 10.

(2) Hence length(seq(0,10,1)) is 11.

(3) Likewise max(seq(0,10,1)) is 10.

(4) Your prob vector is *constant* --- so specifying "prob" makes
     no difference --- the result is the same as if you omitted "prob".

(5) You need to think carefully about what you really mean by "random".
     In what way do you want the final result to be "random"?

I expect that the lecturer who assigned this problem to you  needs to
clarify his/her thinking as well.

cheers,

Rolf Turner

--
Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext. 88276

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