[R] pls help to print out first row of terms(model) output in example program

[Paul Johnson]

Greetings.

I've written a convenience function for multicollinearity diagnosis.
I'd like to report to the user the formula that is used in a
regression.  I get output like this:

> mcDiagnose(m1)
[1] "The following auxiliary models are being estimated and returned in a list:"
[1] "`x1` ~ ."
formula(fmla)()
[1] "`x2` ~ ."

I'd like to fill in the period with the variable names that are in there.

I know the information is in there, I just need to get it.  The terms
output for a fitted model has the output at the very top, in the first
line, above the attributes.  I just want to print out that first line,
here:

> terms(m2)
y ~ log(10 + x1) + poly(x2, 2)
attr(,"variables")
list(y, log(10 + x1), poly(x2, 2))
attr(,"factors")
             log(10 + x1) poly(x2, 2)
y                       0           0
log(10 + x1)            1           0
poly(x2, 2)             0           1
attr(,"term.labels")
[1] "log(10 + x1)" "poly(x2, 2)"
[snip]

In my working example code below , I need the help where I have "##fix
me fix me##


##Paul Johnson
## 2011-12-19
## mcDiagnose.R

lmAuxiliary <- function(model){
  dat <- as.data.frame(model.matrix(model))
  ## ivnames <- attr(delete.response(terms(model)), "term.labels")
  ## previous does not work with transforms like poly
  hasIntercept <- attr(terms(model), "intercept")

  if (hasIntercept) dat <- dat[ , -1] # removes intercept. assumes
intercept in column 1
  ivnames <- colnames(dat)
  print("The following auxiliary models are being estimated and
returned in a list:")

  results <- list()

  for (i in ivnames) {
    fmla <- paste( "`", i, "`", " ~ ." , sep="");
    print(fmla)
    maux <- lm( formula(fmla), data=dat)
    results[[ i ]] <- maux
    print(maux$call[2])
    ###fix me fix me ##
  }
  results
}


mcDiagnose <- function(model){
  auxRegs <- lmAuxiliary(model)
  auxRsq <- numeric(length=length(auxRegs))
  j <- 0
  for ( i in auxRegs ){
    j <- j + 1
    sumry <- summary(i)
    auxRsq[j] <- sumry$r.squared
  }
  print("Drum roll please!")
  print("And your R_j Squareds are (auxiliary Rsq)")
  print(names(auxRegs))
  print(auxRsq)
}

x1 <- rnorm(100)
x2 <- rnorm(100)
y <- rnorm(100)

m1 <- lm(y~x1+x2)

mcDiagnose(m1)


m2 <- lm(y~log(10+x1) + poly(x2,2))

mcDiagnose(m2)

-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas