Efficiently create dummy
well, you can first define a factor, and the use model.matrix(), e.g.,
fc <- factor(c("AR", "DE", "MS", "NY"))
model.matrix(~ fc)
for more info check ?model.matrix(), e.g., if you want to change the
contrasts.
I hope it helps.
Best,
Dimitris
Rob Denniker wrote:
What's the neat way to create a dummy from a list?
The code below is not replicable, but hopefully self-explanatory...
d$treatment<-rep(1,length(d))
notreat<-c("AR", "DE", "MS", "NY", "TN", "AK", "LA", "MD", "NC", "OK", "UT", "VA")
#i would really like this to work:
d$treatment[d$st==any(notreat)]<-0
#but instead i resort to this
for (i in 1:length(notreat)) {
temp.st <- notreat[i]
d$treatment[d$st==temp.st]<-0
i<-i+1 }
Thanks, list!
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Dimitris Rizopoulos Assistant Professor Department of Biostatistics Erasmus University Medical Center Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands Tel: +31/(0)10/7043478 Fax: +31/(0)10/7043014