Hi Josh,
I think,
m <- lm(mpg ~ factor(cyl)+I(mpg^2), data = mtcars)
nd<-get_all_vars(m,data=mtcars)
is what you are after.
cheers.
Am 17.08.2011 04:27, schrieb Joshua Wiley:> Hi All,
>
> I am writing a function to predict values based on a model. It works
> fine as long as the formula just uses regular variable names. I am
> having a problem when the variables are wrapped with a function call.
> For example:
>
> m <- lm(mpg ~ factor(cyl), data = mtcars)
> ## I get the column names using
> as.character(attr(terms(m), "variables"))[-1L]
> ## which gives the same column names as in
> # m$model
>
> predict(m, m$model) # returns an error that 'cyl' is not found
>
> Is there an easy way to get just the variable names or a template data
> frame that I can populate with my own values from a model object? My
> best idea right now is to use a regular expression to strip away
> everything before and after (). This would break down for things like
> I(cyl^2), though.
>
> Any ideas or thoughts would be welcome.
>
> Thanks,
>
> Josh
>
>
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