Get variable names from results of lm()
Hi Marc,
Just to point out some difference,
?x <- 1:20
? y <-? x + (x/4 - 2)^3 + rnorm(20, sd=3)
????? names(y) <- paste("O",x,sep=".")
?????? ww <- rep(1,20); ww[13] <- 0
????? summary(lmxy <- lm(y ~ x + I(x^2)+I(x^3) + I((x-10)^2),
????????????????????????? weights = ww), cor = TRUE)
all.vars(formula(lmxy))
[1] "y" "x"
variable.names(lmxy)
[1] "(Intercept)" "x"?????????? "I(x^2)"????? "I(x^3)"?? A.K. ----- Original Message ----- From: Marc Schwartz <marc_schwartz at me.com> To: Peter Ehlers <ehlers at ucalgary.ca> Cc: "r-help at r-project.org" <r-help at r-project.org>; jdub <jack at ramas.com> Sent: Wednesday, May 23, 2012 3:12 PM Subject: Re: [R] Get variable names from results of lm()
On May 23, 2012, at 1:42 PM, Peter Ehlers wrote:
On 2012-05-23 09:55, R. Michael Weylandt wrote:
I think the easiest that comes to mind is simply names(coef(myMod)) But did you look at myMod$terms[[3]] ? That seems to be the RHS of the formula input (in the few cases I tried) Best, Michael
It depends a bit on just what the OP wants. In case one of the
predictors is a factor, say 'grp' with levels c('A','B','C'), the
coefs will include the names 'grpB' and 'grpC'. If only the
name 'grp' is wanted, one could use myMod$terms[[3]] or
equivalently formula(myMod)[[3]]. It might be instructive for the
OP to look at as.list(formula(myMod)). formula(myMod) is a
language object which has the tilde operator operate on
the LHS (component 2) and the RHS (component 3).
Peter Ehlers
Just to throw out another solution here, the function ?all.vars is helpful: LM <- lm(Petal.Length ~ ., data = iris)
formula(LM)
Petal.Length ~ Sepal.Length + Sepal.Width + Petal.Width + Species
all.vars(formula(LM))
[1] "Petal.Length" "Sepal.Length" "Sepal.Width"? "Petal.Width" [5] "Species"? Regards, Marc Schwartz
On Wed, May 23, 2012 at 10:58 AM, jdub<jack at ramas.com>? wrote:
What is the best way to get the variable names used in lm() from its results? Stumbling around I found I could get the response variable name from myMod$terms[[2]] but using myMod$terms[[1 ]] gives a tilda. I found the names buried in other places in the model object and in the summary of the model, but is there a more direct way, similar to using coef(myMod) to get the coefficients?
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