In tidymodels/discrim: Model Wrappers for Discriminant Analysis

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = "100%"
)

discrim

discrim contains simple bindings to enable the parsnip package to fit various discriminant analysis models, such as

Linear discriminant analysis (LDA, simple and regularized)
Quadratic discriminant analysis (QDA, simple and regularized)
Regularized discriminant analysis (RDA, via Friedman (1989))
Flexible discriminant analysis (FDA) using MARS features
Naive Bayes models

Installation

You can install the released version of discrim from CRAN with:

install.packages("discrim")

And the development version from GitHub with:

# install.packages("pak")
pak::pak("tidymodels/discrim")

Available Engines

The discrim package provides engines for the models in the following table.

library(parsnip)

parsnip_models <- get_from_env("models") %>%
  setNames(., .) %>%
  purrr::map_dfr(get_from_env, .id = "model")

library(discrim)

discrim_models <- get_from_env("models") %>%
  setNames(., .) %>%
  purrr::map_dfr(get_from_env, .id = "model")

dplyr::anti_join(
  discrim_models, parsnip_models, 
  by = c("model", "engine", "mode")
) %>%
  knitr::kable()

Example

Here is a simple model using a simulated two-class data set contained in the package:

#| fig-alt: "Scatter chart. X1 along the x-axis, X2 along the y-axis. points are scattered, with a trend between X1 and X2. Most of the middle points are colored and labeled Class2, with the remaining points labeled Class1. Two connected straight lines, doing its best to separate the two classes."
library(discrim)

parabolic_grid <-
  expand.grid(X1 = seq(-5, 5, length = 100),
              X2 = seq(-5, 5, length = 100))

fda_mod <-
  discrim_flexible(num_terms = 3) %>%
  # increase `num_terms` to find smoother boundaries
  set_engine("earth") %>%
  fit(class ~ ., data = parabolic)

parabolic_grid$fda <-
  predict(fda_mod, parabolic_grid, type = "prob")$.pred_Class1

library(ggplot2)
ggplot(parabolic, aes(x = X1, y = X2)) +
  geom_point(aes(col = class), alpha = .5) +
  geom_contour(data = parabolic_grid, aes(z = fda), col = "black", breaks = .5) +
  theme_bw() +
  theme(legend.position = "top") +
  coord_equal()

Contributing

This project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.

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