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apply the function "factor" to multiple columns
2 messages · Bliese, Paul D LTC USAMH, Dimitris Rizopoulos
you could try this way:
dat <- data.frame(V1 = factor(1:3), V2 = factor(1:3), V3 =
factor(1:3))
dat[1:3] <- lapply(dat[1:3], factor, labels = c("None", "Low Impact",
"MedHigh Imp"))
dat
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: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
----- Original Message -----
From: "Bliese, Paul D LTC USAMH" <paul.bliese at us.army.mil>
To: <r-help at stat.math.ethz.ch>
Sent: Tuesday, May 31, 2005 10:42 AM
Subject: [R] apply the function "factor" to multiple columns
I have a case where I would like to change multiple columns
containing
numbers to factors. I can change each column one at a time as in:
TEMP.FACT$EXPOS01<-factor(TEMP.FACT$EXPOS01,levels=c(1,2,3),labels=c("No
ne","Low Impact","MedHigh Imp"))
TEMP.FACT$EXPOS02<-factor(TEMP.FACT$EXPOS02,levels=c(1,2,3),labels=c("No
ne","Low Impact","MedHigh Imp"))
TEMP.FACT$EXPOS03<-factor(TEMP.FACT$EXPOS03,levels=c(1,2,3),labels=c("No
ne","Low Impact","MedHigh Imp"))
summary(TEMP.FACT[,1:3])
EXPOS01 EXPOS02 EXPOS03
None :219 None :432 None :377
Low Impact :428 Low Impact :248 Low Impact :297
MedHigh Imp:108 MedHigh Imp: 77 MedHigh Imp: 83
NA's : 25 NA's : 23 NA's : 23
It would be much easier, however to use apply as in:
TEMP.FACT
[,1:3]<-apply(TEMP.FACT[,1:3],2,factor,labels=c("None","Low
Impact","MedHigh Imp"))
This appears to work (no error messages); however, this does not
actually change the variables to factors. That is they are still
treated as numbers:
summary(TEMP.FACT[,1:3])
EXPOS01 EXPOS02 EXPOS03 Min. : 1.000 Min. : 1.000 Min. : 1.000 1st Qu.: 1.000 1st Qu.: 1.000 1st Qu.: 1.000 Median : 2.000 Median : 1.000 Median : 2.000 Mean : 1.853 Mean : 1.531 Mean : 1.612 3rd Qu.: 2.000 3rd Qu.: 2.000 3rd Qu.: 2.000 Max. : 3.000 Max. : 3.000 Max. : 3.000 NA's :25.000 NA's :23.000 NA's :23.000 Any ideas on how I could efficiently change a lot of columns to factors? Thanks, PB [[alternative HTML version deleted]]
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