[R] how to generate argument from a vector automatically

[Uwe Ligges]

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.

You have to construct it as.formula() from these characters,
or even better use short term formulas such as "y~.", if all variables
should be used anyway.

Uwe Ligges

> could anybody give me a hint?
> 
> 
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