[R] Multiple Conditional Tranformations

[Gabor Grothendieck]

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>
> =========================================================
>
>
>
>
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