Hi I want to sample from a discrete random variable X, defined on the non-negative integers, with prob(X=0) = (1-p) prob(X=1) = (1-p)*p ... prob(X=i)=(1-p)*p^i ... Before reinventing the wheel, is there a ready-made R function to give me such a thing? -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743
discrete probability distribution
3 messages · robin hankin, Matthias Kohl, (Ted Harding)
Hi, have a look at http://mathworld.wolfram.com/GeometricDistribution.html respectively http://mathworld.wolfram.com/NegativeBinomialDistribution.html with r = 1. In R have a look at ?rnbinom with n = 1 and in your case: prob = 1-p hth Matthias
Hi I want to sample from a discrete random variable X, defined on the non-negative integers, with prob(X=0) = (1-p) prob(X=1) = (1-p)*p ... prob(X=i)=(1-p)*p^i ... Before reinventing the wheel, is there a ready-made R function to give me such a thing? -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743
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On 23-Feb-06 Robin Hankin wrote:
Hi I want to sample from a discrete random variable X, defined on the non-negative integers, with prob(X=0) = (1-p) prob(X=1) = (1-p)*p ... prob(X=i)=(1-p)*p^i ... Before reinventing the wheel, is there a ready-made R function to give me such a thing?
Use rgeom(n,(1-p)) Note (from ?rgeom) that these functions use the definition P(n) = p*(1-p)^n i.e. the complementary value of p to the one in your description. Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 23-Feb-06 Time: 09:18:50 ------------------------------ XFMail ------------------------------