[R] Multiple Conditional Tranformations

[Muenchen, Robert A (Bob)]

Mark,

Here's what I get when I try that approach.

Thanks,
Bob

> mydata$score1<-numeric(mydata$q1) #just initializing.
> mydata$score2<-numeric(mydata$q1)
> mydata$score1<-NA
> mydata$score2<-NA
> mydata
  group gender q1 q2 q3 q4 score1 score2
1     1      f  2  2  5  4     NA     NA
2     2      f  2  1  4  5     NA     NA
3     1      f  2  2  4  4     NA     NA
4     2      f  1  1  5  5     NA     NA
5     1      m  4  5  4 NA     NA     NA
6     2      m  5  4  5  5     NA     NA
7     1      m  3  3  4  5     NA     NA
8     2      m  5  5  5  4     NA     NA
> mydata$score1[mydata$gender == "f"]<-2*mydata$q1 + mydata$q2
Warning message:
number of items to replace is not a multiple of replacement length 
> mydata$score2[mydata$gender == "f"]<-2.5*mydata$q1 + mydata$q2
Warning message:
number of items to replace is not a multiple of replacement length 
> mydata$score1[mydata$gender == "m"]<-3*mydata$q1 + mydata$q2
Warning message:
number of items to replace is not a multiple of replacement length 
> mydata$score2[mydata$gender == "m"]<-3.5*mydata$q1 + mydata$q2
Warning message:
number of items to replace is not a multiple of replacement length 
>

-----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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