[R] Random number datasets help

[Nordlund, Dan (DSHS/RDA)]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of Henrique Dallazuanna
> Sent: Thursday, June 18, 2009 10:52 AM
> To: Alexandre Lockhart
> Cc: r-help at r-project.org
> Subject: Re: [R] Random number datasets help
> 
> Try this also:
> 
> a <- expand.grid(a1, a2)
> x <- mapply(rnorm, n = 500, mean = a[,1], sd = a[,2])
> 
> On Thu, Jun 18, 2009 at 2:10 PM, Alexandre Lockhart <
> alexandre_georges at hotmail.com> wrote:
> 
> >
> > Hello:
> >
> > My problem is that I have a data frame of means, and a data frame of
> > standard deviations which match up to each mean.  I have been trying to
> > create 500 random numbers in a given dataset for each mean/sd combination,
> > but I am only able to generate the last value in each data set to create one
> > dataset (there should be 28 in all).  Examining my code, what can I change
> > to generate 28 datasets based on respective mean and sds?
> >
> >
> > a1<-
> c(178.07,178.28,178.08,177.74,177.04,178.17,177.58,57.71,59.6,60.92,59.48,59.32,
> 61.59,59.94,28.9,29.82,30.73,25.68,27.93,28.98,29.76,123.48,127.27,127.8,127.2,1
> 27.13,126.71,125.5)
> >
> > a2<-
> c(1.69,1.3,1,.18,1.53,1.31,1.35,1.83,1.56,1.12,.74,1.48,1.67,1.53,.95,.87,0.03,1.12,1.
> 95,1.22,1.04,1.64,1.83,1,1,1.08,1.35,2.37)
> > for(i in 1:length(a1))
> >    for(j in 1:length(a2))
> >        x<-rnorm(500,mean=a1[i],sd=a2[j])
> >
> > Thank you,
> >
> > Agl
> >
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> 
> 
> --
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
> 
Since the original post said that he wanted 28 samples of 500, what may be wanted is

x <- mapply(rnorm, n = 500, mean = a1, sd = a2)

Hope this is helpful,

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA  98504-5204