Extended Formulas in R

Overview

Infrastructure for extended formulas in R with multiple parts on the right-hand side and/or multiple responses on the left-hand side.

Get started

Extended Formula with two right-hand sides for mtcars data:

library("Formula")
f <- Formula(log(mpg) ~ disp | factor(vs))
mf <- model.frame(f, data = head(mtcars, 3))

Extract response and both regressor matrices from model frame:

model.response(mf)
##     Mazda RX4 Mazda RX4 Wag    Datsun 710 
##      3.044522      3.044522      3.126761
model.matrix(f, data = mf, rhs = 1)
##               (Intercept) disp
## Mazda RX4               1  160
## Mazda RX4 Wag           1  160
## Datsun 710              1  108
## attr(,"assign")
## [1] 0 1
model.matrix(f, data = mf, rhs = 2)
##               (Intercept) factor(vs)1
## Mazda RX4               1           0
## Mazda RX4 Wag           1           0
## Datsun 710              1           1
## attr(,"assign")
## [1] 0 1
## attr(,"contrasts")
## attr(,"contrasts")$`factor(vs)`
## [1] "contr.treatment"

Reference

Zeileis A, Croissant Y (2010). “Extended Model Formulas in R: Multiple Parts and Multiple Responses. Journal of Statistical Software, 34(1), 1-13. doi:10.18637/jss.v034.i01

Installation

The stable version of Formula is available from CRAN:

install.packages("Formula")

The latest development version can be installed from R-universe:

install.packages("Formula", repos = "https://zeileis.R-universe.dev")

License

The package is available under the General Public License version 3 or version 2