Infrastructure for extended formulas in R with multiple parts on the right-hand side and/or multiple responses on the left-hand side.
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"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
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")The package is available under the General Public License version 3 or version 2