poissonreg enables the parsnip package to fit various types of Poisson regression models including ordinary generalized linear models, simple Bayesian models (via rstanarm), and two zero-inflated Poisson models (via pscl).
A log-linear model for catgorical data analysis:
library(poissonreg)
# 3D contingency table from Agresti (2007):
poisson_reg() %>%
set_engine("glm") %>%
fit(count ~ (.)^2, data = seniors)
#> parsnip model object
#>
#> Fit time: 2ms
#>
#> Call: stats::glm(formula = formula, family = stats::poisson, data = data)
#>
#> Coefficients:
#> (Intercept) marijuanayes cigaretteyes
#> 5.6334 -5.3090 -1.8867
#> alcoholyes marijuanayes:cigaretteyes marijuanayes:alcoholyes
#> 0.4877 2.8479 2.9860
#> cigaretteyes:alcoholyes
#> 2.0545
#>
#> Degrees of Freedom: 7 Total (i.e. Null); 1 Residual
#> Null Deviance: 2851
#> Residual Deviance: 0.374 AIC: 63.42