autoplot.compare_to_leader: Visualize How Models Compare to the Leader

Description

Two panels are drawn side-by-side: the posterior distribution of the metric for each model (as a median and credible interval) and the probability that each model differs from the leader.

Usage

# S3 method for compare_to_leader
autoplot(object, zero_bar = 0.01, metric_label = NULL, ...)

Value

A patchwork::patchwork object made from two ggplot2::ggplot()

objects.

Arguments

object: An object produced by compare_to_leader().
zero_bar: A single number giving the shortest bar to draw in the right-hand panel. Probabilities of zero would otherwise draw a bar with no length, which reads as a missing row rather than a zero. Set it to 0 to draw the probabilities exactly.
metric_label: A single character string or expression used to label the x-axis of the left-hand panel. If NULL, the name of the metric recorded by perf_mod() is used. This is useful for spelling a metric out or adding units, such as "RMSE (kg)".
...: Not currently used.

Details

The right-hand panel shows pract_equiv when compare_to_leader() was given a size and pr_worse otherwise. In both cases the fill scale is oriented so that darker bars are better.

Note that zero_bar makes a bar's length depart from the probability it represents: any value below zero_bar is drawn at zero_bar. The fill colour is always mapped to the true value, and the leader always has a pr_worse of exactly zero.

Models are ordered by rank along the y-axis, running from the worst at the top to the leader at the bottom.

The left-hand panel is labelled with the metric name when one is available. A perf_mod object always records one, but a compare_to_leader() result that has been through a dplyr verb will have lost the attribute, in which case the axis falls back to "Posterior". Use metric_label to set it directly.

Examples

Run this code

library(parsnip)
library(rsample)
library(workflowsets)

set.seed(1)
folds <- vfold_cv(mtcars, v = 5)

# \donttest{
mpg_models <-
  workflow_set(
    preproc = list(
      small = mpg ~ wt,
      medium = mpg ~ wt + hp,
      large = mpg ~ .
    ),
    models = list(lm = linear_reg())
  ) |>
  workflow_map("fit_resamples", resamples = folds, seed = 2)

set.seed(4321)
mpg_post <- perf_mod(mpg_models, metric = "rmse", refresh = 0, chains = 2)

mpg_res <- compare_to_leader(mpg_post, size = 0.5, seed = 2)
autoplot(mpg_res)

# Spell the metric out and give it units:
autoplot(mpg_res, metric_label = "RMSE (miles per gallon)")
# }