[R] Conditionally swap two columns of a data.frame?

[Dimitris Rizopoulos]

type "help.start()" in the R console or open manually the "C:\Program
Files\R\rw1091\doc\html\rwin.html" file and you will get all the
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Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/396887
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Dan Bolser" <dmb at mrc-dunn.cam.ac.uk>
To: "Dimitris Rizopoulos" <dimitris.rizopoulos at med.kuleuven.ac.be>
Cc: <r-help at stat.math.ethz.ch>
Sent: Thursday, September 16, 2004 2:55 PM
Subject: Re: [R] Conditionally swap two columns of a data.frame?


>
> Minter!
>
> Is there an R cookbook? which lists this kind of common problem and
common
> solution?
>
>
> On Thu, 16 Sep 2004, Dimitris Rizopoulos wrote:
>
> >Hi Dan,
> >
> >do you need something like that,
> >
> >dat <- data.frame(V1=rnorm(40000, 10), V2=rnorm(40000, 10))
> >ratioV1V2 <- ifelse(dat$V1>dat$V2, dat$V1/dat$V2, dat$V2/dat$V1)
> >
> >I hope it helps.
> >
> >Best,
> >Dimitris
> >
> >----
> >Dimitris Rizopoulos
> >Ph.D. Student
> >Biostatistical Centre
> >School of Public Health
> >Catholic University of Leuven
> >
> >Address: Kapucijnenvoer 35, Leuven, Belgium
> >Tel: +32/16/396887
> >Fax: +32/16/337015
> >Web: http://www.med.kuleuven.ac.be/biostat/
> >     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
> >
> >----- Original Message ----- 
> >From: "Dan Bolser" <dmb at mrc-dunn.cam.ac.uk>
> >To: <r-help at stat.math.ethz.ch>
> >Sent: Thursday, September 16, 2004 2:19 PM
> >Subject: [R] Conditionally swap two columns of a data.frame?
> >
> >
> >>
> >> I am doing this a kinda dumb way, and it is apparetnly taking
> >> forever.
> >>
> >> I have a data frame with two numeric columns. I want to look at
> >their
> >> correlation, and I am looking at the size ratio between the two.
> >>
> >> i.e.
> >>
> >> plot(density(data$V1/data$V2))
> >>
> >> This kinda gives me a normal curve showing something about the
> >> distribution of the two values.
> >>
> >> I want to make sure that V1/V2 is always > 1 ...
> >>
> >> for (i in 1:length(row.names(data)) ){
> >>   ratioV1V2 <- if(V1>V2) V1/V2 else V2/V1
> >> }
> >>
> >> This is a bit of a hack, and is taking forever for some reson
(about
> >> 40,000 rows in my data.frame).
> >>
> >> I would just like to swap the values in the data frame (to put
the
> >bigest
> >> first for example), then use the above plot to get what I want.
> >>
> >> Should I use the DB backend to the data to make the dump in this
> >way?
> >> (involves some hacky sql)
> >>
> >> Considering I am interested in the range of the ratio between V1
and
> >V2,
> >> should I be looking at doing a different analysis?
> >>
> >> I am so dumb, any help is appreciated,
> >>
> >> Dan.
> >>
> >> ______________________________________________
> >> R-help at stat.math.ethz.ch mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide!
> >http://www.R-project.org/posting-guide.html
> >>
> >
>