Supplying several names to a function call

Question

This is a function from an earlier question of mine: How to let R predict user input I would like to make it easier to supply several names to the xname argument but I still can't fugure out just how to do that.

lmfun<-function(df,yname,xname){
  y<-deparse(substitute(yname))
  x<-deparse(substitute(xname))
  f<-as.formula(paste0(y,"~",x))
  lm.fit<-do.call("lm",list(data=quote(df),f))
  coef(lm.fit)
}

Here's what I've tried

vals<-names(mtcars)[-1]
lmfun(mtcars,mpg,disp)#This works

How can I best make this work? I've tried several other ways but showing only this:

for(name in 1:seq_along(vals)){
  name<-eval(substitute(name))
  lmfun(mtcars,mpg,name)
}

This fails:

Error in deparse(substitute(xname)) : 'arg' should be one of “mpg”, “cyl”, “disp”, “hp”, “drat”, “wt”, “qsec”, “vs”, “am”, “gear”, “carb”

Also tried:

for(name in 1:length(vals)){
  vals<-noquote(vals)
 lmfun(mtcars,mpg,vals[name])
}

I would also appreciate if I could be pointed at a way to incorporate multilinear regression. That is xname+xname1+xname2 Thanks!

I am thinking of making it "easy" for one to just add a name without having to use strings. tbh, it's mainly for learning purposes. — NelsonGon

G. Grothendieck G. Grothendieck · Accepted Answer · 2019-01-27T17:05:04

Invoke lmfun using do.call like this:

lapply(vals, function(val) do.call("lmfun", list(mtcars, quote(mpg), as.name(val))))

This also works although generally code which does not use eval is preferred when possible:

lapply(vals, 
  function(val) eval(substitute(lmfun(mtcars, mpg, val), list(val = as.name(val)))))

Supplying several names to a function call

2 Answers