[R] how to generate argument from a vector automatically
Adaikalavan Ramasamy
ramasamy at cancer.org.uk
Tue Jul 12 12:52:37 CEST 2005
You can do it by subsetting the dataframe
df <- data.frame( y=rbinom(100, 1, prob=0.5),
x1=rnorm(100), x2=rnorm(100), x3=rnorm(100),
z1=rnorm(100), z2=rnorm(100) )
names <- c("x1", "x2", "x3")
tree( y ~ . , data = df[ , c("y", names) ] )
This solution is useless when you want to consider interactions between
some terms etc. Another more flexible solution is from last example from
help(formula) :
xnam <- paste("x", 1:3, sep="")
call <- as.formula(paste("y ~ ", paste(xnam, collapse= "+")))
tree( call, df )
Regards, Adai
On Tue, 2005-07-12 at 09:53 +0000, zhihua li wrote:
> hi netters
>
> i have a vector NAMES containing a series of variable names:
> NAMES=c(x,r,z,m,st,qr,.....nn).
> i wanna fit a regression tree by using the code:
> my.tree<-tree(y~x+r+z+m+....nn,my.dataframe)
>
> but i don't want to type out "x+r+z+m+....+nn" one by one, as there are so
> many variables. besides, sometimes i wanna put the code in a function. so i
> need to have the argument "x+r+z+m+....+nn" generated from NAMES
> automatically.
>
> i've tried the code: paste(X,collpase="+") but it didn't work.
>
> could anybody give me a hint?
>
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