Create a data frame with just the variables in the formula in
a `lm`

object.
This is comparable to `model.matrix`

or `model.frame`

except that factors,
polynomials, transformations, etc. are not expanded.

`model.data(lmobj, lhs = FALSE)`

lmobj

An object returned by `lm`

or one of its relatives.

lhs

Boolean indicator of whether or not to include the variable(s) on the left-hand side of the model formula.

A data frame containing each of the variables referenced in the model formula.

This is an easy-to-use substitute for `get_all_vars`

.
The `formula`

, `data`

, and `subset`

arguments, if present in
`lmobj`

's call, affect the result appropriately.

Lenth RV (2009) ``Response-Surface Methods in R, Using rsm'',
*Journal of Statistical Software*, 32(7), 1--17.
https://www.jstatsoft.org/v32/i07/.

# NOT RUN { library(rsm) trees.lm <- lm(log(Volume) ~ poly(log(Girth),3), data = trees, subset = 1:20) model.frame(trees.lm) model.data(trees.lm) # }