[R] Converting factors to bounded random numerical data

[David L Carlson]

This should work:

> a <- data.frame(X=rnorm(25, 20, 4), Y=rnorm(25, 15, 3), 
     Z=sample(c(LETTERS[1:3]), 25, replace=TRUE))
> head(a)
          X         Y Z
1  17.77449 14.425221 B
2  19.95400 13.408439 A
3  13.40162 12.219984 A
4  15.89822 19.214026 B
5  18.55717 14.568691 B
6  19.86619 11.606099 B
> Zfact <- data.frame(factor=LETTERS[1:3], low=c(1, 5, 10), high=c(4, 9,
12))
> Zfact
  factor low high
1      A   1    4
2      B   5    9
3      C  10   12
> set.seed(42)
> a$Zval <- runif(nrow(a), Zfact$low[as.numeric(a$Z)],
Zfact$high[as.numeric(a$Z)])
> head(a, 10)
          X        Y Z      Zval
1  17.77449 14.42522 B  8.659224
2  19.95400 13.40844 A  3.811226
3  13.40162 12.21998 A  1.858419
4  15.89822 19.21403 B  8.321791
5  18.55717 14.56869 B  7.566982
6  19.86619 11.60610 B  7.076384
7  14.72275 18.38715 A  3.209765
8  26.09711 17.79988 C 10.269333
9  18.72558 15.64477 C 11.313985
10 17.33280 19.03034 B  7.820259

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of jim holtman
> Sent: Wednesday, October 10, 2012 8:32 PM
> To: KoopaTrooper
> Cc: r-help at r-project.org
> Subject: Re: [R] Converting factors to bounded random numerical data
> 
> You need to include how many random numbers you want to create; you
> are asking for only 1, that is why they are are the same.  You
> probably want something like:
> 
> a$Z<-ifelse(a$Z=="L"
>     ,sample(1:4, nrow(a), TRUE)
>     ,ifelse(a$Z=="M"
>         ,sample(5:9, nrow(a), TRUE)
>         ,ifelse(a$Z=="U"
>             ,sample(10:12, nrow(a), TRUE)
>             , -42  # you had a character which would have converted
> everything to character
>             )
>         )
>     )
> 
> On Wed, Oct 10, 2012 at 8:36 PM, KoopaTrooper <ncooper1 at tulane.edu>
> wrote:
> > I have a data set (a) with three columns (X,Y,Z). The first 2 columns
> are
> > numeric. The third (Z) is a factor with three levels A,B,C. I want to
> turn
> > each A into a different random number between 1 and 4, each B into a
> > different random number between 5 and 8, etc.
> >
> > I tried this:
> >
> > a$Z<-
> ifelse(a$Z=="L",sample(1:4,1),ifelse(a$Z=="M",sample(5:9,1),ifelse(a$Z=
> ="U",sample(10:12,1),"")
> >
> > and it almost worked but changed all the "A's" into the same random
> number.
> > I need a different random number for each A. Ideas?
> >
> > Thanks,
> >
> >
> >
> > --
> > View this message in context:
> http://r.789695.n4.nabble.com/Converting-factors-to-bounded-random-
> numerical-data-tp4645801.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
> > R-help at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> 
> 
> 
> --
> Jim Holtman
> Data Munger Guru
> 
> What is the problem that you are trying to solve?
> Tell me what you want to do, not how you want to do it.
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.