[R] Converting factors to bounded random numerical data

David L Carlson dcarlson at tamu.edu
Thu Oct 11 05:45:06 CEST 2012 

I forgot that you were looking for whole numbers:

> Zfact <- data.frame(factor=LETTERS[1:3], low=c(.5, 4.5, 9.5), 
     high=c(4.499, 9.499, 12.499))
> Zfact
  factor low   high
1      A 0.5  4.499
2      B 4.5  9.499
3      C 9.5 12.499
> set.seed(42)
> a$Zval <- round(runif(nrow(a), Zfact$low[as.numeric(a$Z)],
      Zfact$high[as.numeric(a$Z)]), 0)
> head(a, 10)
> head(a, 10)
          X        Y Z Zval
1  17.77449 14.42522 B    9
2  19.95400 13.40844 A    4
3  13.40162 12.21998 A    2
4  15.89822 19.21403 B    9
5  18.55717 14.56869 B    8
6  19.86619 11.60610 B    7
7  14.72275 18.38715 A    3
8  26.09711 17.79988 C   10
9  18.72558 15.64477 C   11

----------------------------------------------
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 David L Carlson
> Sent: Wednesday, October 10, 2012 10:30 PM
> To: 'jim holtman'; 'KoopaTrooper'
> Cc: r-help at r-project.org
> Subject: Re: [R] Converting factors to bounded random numerical data
> 
> 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.
> 
> ______________________________________________
> 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.

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