[R] Multiple Conditional Tranformations

[Muenchen, Robert A (Bob)]

That's exactly what I'm looking for. Thanks so much for taking the time
to do it that way. 

On the redundancy issue, I think SAS checks the "else if" condition only
if the original "if" is false. The check for f when not m I put in only
to exclude missing values for gender.

Thanks!!
Bob

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Sent: Saturday, November 25, 2006 7:37 AM
To: Muenchen, Robert A (Bob)
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] Multiple Conditional Tranformations

Firstly your outline does not check once, it checks twice.  First it
check for "m" and then it redundantly checks for "f".  On the other
hand the two variations in my post do check once.

Although substantially longer than the solutions in my prior posts,
if you want the style shown in your post try this:

mydata2 <- cbind(mydata, score1 = 0, score2 = 0)
is.m <- mydata$gender == "m"

mydata2[is.m, ] <- transform(mydata[is.m, ],
   score1 = 3 * q1 + q2,
   score2 = 3.5 * q1 + q2
)

mydata2[!is.m,] <- transform(mydata2[!is.m, ],
   score1 = 2 * q1 + q2,
   score2 = 2.5 * q1 + q2
)

On 11/25/06, Muenchen, Robert A (Bob) <muenchen at utk.edu> wrote:
> Gabor,
>
> Those are handy variations! Perhaps my brain in still in SAS mode on
> this. I'm expecting something like the code below that checks for male
> only once, checks for female only when not male (skipping NAs) and
does
> all formulas under the appropriate conditions. The formulas I made up
to
> keep the code short & may not be as easily modified to let the logical
> 0/1 values fix them.
>
> if gender=="m" then do;
>  Score1=...
>  Score2=
>  ...
> end;
> else if gender=="f" then do;
>  Score1=...
>  Score2=
>  ...
> end;
>
> R may not have anything quite like that. R certainly has many other
> features that SAS lacks.
>
> Thanks,
> Bob
>
> =========================================================
> Bob Muenchen (pronounced Min'-chen), Manager
> Statistical Consulting Center
> U of TN Office of Information Technology
> 200 Stokely Management Center, Knoxville, TN 37996-0520
> Voice: (865) 974-5230
> FAX: (865) 974-4810
> Email: muenchen at utk.edu
> Web: http://oit.utk.edu/scc,
> News: http://listserv.utk.edu/archives/statnews.html
> =========================================================
>
>
> -----Original Message-----
> From: Gabor Grothendieck [mailto:ggrothendieck at gmail.com]
> Sent: Saturday, November 25, 2006 12:39 AM
> To: Muenchen, Robert A (Bob)
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] Multiple Conditional Tranformations
>
> And here is a variation:
>
> transform(mydata,
>   score1 = (2 + (gender == "m")) * q1 + q2,
>   score2 = score1 + 0.5 * q1
> )
>
> or
>
> transform(
>   transform(mydata, score1 = (2 + (gender == "m")) * q1 + q2),
>   score2 = score1 + 0.5 * q1
> )
>
>
> On 11/25/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > Try this:
> >
> >
> > transform(mydata,
> >   score1 = (2   + (gender == "m")) * q1 + q2,
> >   score2 = (2.5 + (gender == "m")) * q1 + q2
> > )
> >
> >
> > On 11/24/06, Muenchen, Robert A (Bob) <muenchen at utk.edu> wrote:
> > > Mark,
> > >
> > > I finally got that approach to work by spreading the logical
> condition
> > > everywhere. That gets the lengths to match. Still, I can't help
but
> > > think there must be a way to specify the logic once per condition.
> > >
> > > Thanks,
> > > Bob
> > >
> > > mydata$score1<-numeric(mydata$q1) #just initializing.
> > > mydata$score2<-numeric(mydata$q1)
> > > mydata$score1<-NA
> > > mydata$score2<-NA
> > > mydata
> > >
> > > mydata$score1[mydata$gender == "f"]<-
> 2*mydata$q1[mydata$gender=="f"] +
> > >
> > >  mydata$q2[mydata$gender=="f"]
> > > mydata$score2[mydata$gender ==
> "f"]<-2.5*mydata$q1[mydata$gender=="f"] +
> > >
> > >  mydata$q2[mydata$gender=="f"]
> > > mydata$score1[mydata$gender ==
"m"]<-3*mydata$q1[mydata$gender=="m"]
> +
> > >  mydata$q2[mydata$gender=="m"]
> > > mydata$score2[mydata$gender ==
> "m"]<-3.5*mydata$q1[mydata$gender=="m"] +
> > >
> > >  mydata$q2[mydata$gender=="m"]
> > > mydata
> > >
> > > =========================================================
> > > Bob Muenchen (pronounced Min'-chen), Manager
> > > Statistical Consulting Center
> > > U of TN Office of Information Technology
> > > 200 Stokely Management Center, Knoxville, TN 37996-0520
> > > Voice: (865) 974-5230
> > > FAX: (865) 974-4810
> > > Email: muenchen at utk.edu
> > > Web: http://oit.utk.edu/scc,
> > > News: http://listserv.utk.edu/archives/statnews.html
> > > =========================================================
> > >
> > >
> > > -----Original Message-----
> > > From: Leeds, Mark (IED) [mailto:Mark.Leeds at morganstanley.com]
> > > Sent: Friday, November 24, 2006 8:45 PM
> > > To: Muenchen, Robert A (Bob)
> > > Subject: RE: [R] Multiple Conditional Tranformations
> > >
> > > I'm not sure if I understand your question but I don't think you
> need
> > > iflelse statements.
> > >
> > > myscore<-numeric(q1) ( because I'm not sure how to initialize a
list
> so
> > > initialize a vector with q1 elements )
> > >
> > > myscore<-NA ( I think this should set all the values in myscore to
> NA )
> > > myscore[mydata$gender == f]<-2*mydata$q1 + mydata$q2
> > > myscore[mydata$gender == m]<-3*mydata$q1 + mydata$q2
> > >
> > > the above should do what you do in the first part of your code but
I
> > > don't know if that was your question ?
> > > also, it does it making myscore a vector because I didn't know how
> to
> > > initialize a list.
> > > Someone else may goive a better solution. I'm no expert.
> > >
> > >
> > > -----Original Message-----
> > > From: r-help-bounces at stat.math.ethz.ch
> > > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Muenchen,
> Robert
> > > A (Bob)
> > > Sent: Friday, November 24, 2006 8:27 PM
> > > To: r-help at stat.math.ethz.ch
> > > Subject: [R] Multiple Conditional Tranformations
> > >
> > > Greetings,
> > >
> > >
> > >
> > > I'm learning R and I'm stuck on a basic concept: how to specify a
> > > logical condition once and then perform multiple transformations
> under
> > > that condition. The program below is simplified to demonstrate the
> goal.
> > > Its results are exactly what I want, but I would like to check the
> > > logical state of gender only once and create both (or any number
of)
> > > scores at once.
> > >
> > >
> > >
> > > mystring<-
> > >
> > > ("id,group,gender,q1,q2,q3,q4
> > >
> > > 01,1,f,2,2,5,4
> > >
> > > 02,2,f,2,1,4,5
> > >
> > > 03,1,f,2,2,4,4
> > >
> > > 04,2,f,1,1,5,5
> > >
> > > 05,1,m,4,5,4,
> > >
> > > 06,2,m,5,4,5,5
> > >
> > > 07,1,m,3,3,4,5
> > >
> > > 08,2,m,5,5,5,4")
> > >
> > >
> > >
> > >
>
mydata<-read.table(textConnection(mystring),header=TRUE,sep=",",row.name
> > > s="id")
> > >
> > > mydata
> > >
> > >
> > >
> > > #Create score1 so that it differs for males and females:
> > >
> > > mydata$score1 <- ifelse( mydata$gender=="f" ,
> > >
> > >   (mydata$score1 <- (2*mydata$q1)+mydata$q2),
> > >
> > >   ifelse( mydata$gender=="m",
> > >
> > >      (mydata$score1 <- (3*mydata$q1)+mydata$q2), NA )
> > >
> > >   )
> > >
> > > mydata
> > >
> > >
> > >
> > > #Create score2 so that it too differs for males and females:
> > >
> > > mydata$score2 <- ifelse( mydata$gender=="f" ,
> > >
> > >   (mydata$score2 <- (2.5*mydata$q1)+mydata$q2),
> > >
> > >   ifelse( mydata$gender=="m",
> > >
> > >      (mydata$score2 <- (3.5*mydata$q1)+mydata$q2), NA )
> > >
> > >   )
> > >
> > > mydata
> > >
> > >
> > >
> > >
> > >
> > > Thanks!
> > >
> > > Bob
> > >
> > > =========================================================
> > > Bob Muenchen (pronounced Min'-chen), Manager Statistical
Consulting
> > > Center U of TN Office of Information Technology 200 Stokely
> Management
> > > Center, Knoxville, TN 37996-0520
> > > Voice: (865) 974-5230
> > > FAX: (865) 974-4810
> > > Email: muenchen at utk.edu
> > > Web: http://oit.utk.edu/scc <http://oit.utk.edu/scc> ,
> > > News: http://listserv.utk.edu/archives/statnews.html
> > > <http://listserv.utk.edu/archives/statnews.html>
> > > =========================================================
> > >
> > >
> > >
> > >
> > >        [[alternative HTML version deleted]]
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