[R] Multiple Conditional Tranformations

Sat Nov 25 12:46:18 CET 2006

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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