R help - Jul 2002 - Discrete random variable

Hi,

I would create a function rdiscrete that returns the value of a discrete random
variable X defined on a subset which can change, and for the same probability
for
the issue, eg:
X could sometimes take a value in the subset {2,3,4} with probability 1/3 for
each
issue,
and sometimes X could take a value in the subset {2,3,4,5,6} with probability
1/5 for each
issue,
etc.

The function should have one parameter only: a vector, composed by the values of
the definition subset of X.

Thank your for your help,
Tristan Lorino

---------------------- 
?cole Nationale V?t?rinaire d'Alfort - http://www.vet-alfort.fr,
T?l. 01 43 96 70 33
M?l. tlorino at vet-alfort.fr
Site personnel : http://daedale.free.fr

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On Mon, 1 Jul 2002 tlorino at vet-alfort.fr wrote:
> I would create a function rdiscrete that returns the value of a discrete
random
There already is a function rdiscrete in package e1071 which does what I
would expect a function of that name to do.
> variable X defined on a subset which can change, and for the same
probability for
> the issue, eg:
> X could sometimes take a value in the subset {2,3,4} with probability 1/3
for each
> issue,
> and sometimes X could take a value in the subset {2,3,4,5,6} with
probability
> 1/5 for each
> issue,
> etc.
>
> The function should have one parameter only: a vector, composed by the
values of
> the definition subset of X.
?sample, specifically sample(subset, 1).


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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> Hi,
> 
> I would create a function rdiscrete that returns the value of a discrete
random
> variable X defined on a subset which can change, and for the same
probability for
> the issue, eg:
> X could sometimes take a value in the subset {2,3,4} with probability 1/3
for each
> issue,
> and sometimes X could take a value in the subset {2,3,4,5,6} with
probability
> 1/5 for each
> issue,
> etc.
> 
> The function should have one parameter only: a vector, composed by the
values of
> the definition subset of X.
have a look at `sample', 

Torsten
> 
> Thank your for your help,
> Tristan Lorino
> 
> ---------------------- 
> ?cole Nationale V?t?rinaire d'Alfort - http://www.vet-alfort.fr,
> T?l. 01 43 96 70 33
> M?l. tlorino at vet-alfort.fr
> Site personnel : http://daedale.free.fr
> 
>
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> r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
> Send "info", "help", or "[un]subscribe"
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>
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> 
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Hi Tristan,

how about:

choose.from<-function(x) { x[ceiling(runif(1,0,length(x)))]}

Cheers,

Mike.

     > -----Original Message-----
     > From: owner-r-help at stat.math.ethz.ch
     > [mailto:owner-r-help at stat.math.ethz.ch]On Behalf Of
     > tlorino at vet-alfort.fr
     > Sent: 01 July 2002 10:24
     > To: r-help at stat.math.ethz.ch
     > Subject: [R] Discrete random variable
     >
     >
     > Hi,
     >
     > I would create a function rdiscrete that returns the value
     > of a discrete random
     > variable X defined on a subset which can change, and for the
     > same probability for
     > the issue, eg:
     > X could sometimes take a value in the subset {2,3,4} with
     > probability 1/3 for each
     > issue,
     > and sometimes X could take a value in the subset {2,3,4,5,6}
     > with probability
     > 1/5 for each
     > issue,
     > etc.
     >
     > The function should have one parameter only: a vector,
     > composed by the values of
     > the definition subset of X.
     >
     > Thank your for your help,
     > Tristan Lorino
     >
     > ----------------------
     > ?cole Nationale V?t?rinaire d'Alfort - http://www.vet-alfort.fr,
     > T?l. 01 43 96 70 33
     > M?l. tlorino at vet-alfort.fr
     > Site personnel : http://daedale.free.fr
     >
     > -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
     > .-.-.-.-.-.-.-.-.-
     > r-help mailing list -- Read
http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
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_._

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