[R] Error in plot.lm

[Jeff Newmiller]

I am encountering an error with plot.lm:

> tstdf <- data.frame( y=c(1.01,1.98,3.02,3.99),x=c(1,2,3,4))
> plot(lm(I(y) ~ x, data=tstdf))
Hit <Return> to see next plot:
Hit <Return> to see next plot:
Error in object$coefficients : $ operator is invalid for atomic vectors

Obviously I don't need the I() in this example, but I have been working
with regressions that involve an expression on the left side of the 
formula, for which I do need the I().  I can work around by declaring a 
new actual column with the computed result, but this seems otherwise 
unnecessary.

Is this behaviour intended?

> R.Version()
$platform
[1] "i386-pc-mingw32"

$arch
[1] "i386"

$os
[1] "mingw32"

$system
[1] "i386, mingw32"

$status
[1] ""

$major
[1] "2"

$minor
[1] "12.1"

$year
[1] "2010"

$month
[1] "12"

$day
[1] "16"

$`svn rev`
[1] "53855"

$language
[1] "R"

$version.string
[1] "R version 2.12.1 (2010-12-16)"


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