roc {triptych}

Evaluation of forecasts using ROC curves

Description

A ROC curve visualizes discrimination ability by displaying the hit rate against the false alarm rate for all threshold values.

Usage

roc(x, y_var = "y", ..., y = NULL, concave = TRUE)

as_roc(x, r)

Arguments

x

A data frame, list, matrix, or other object that can be coerced to a tibble. Contains numeric forecasts, and observations (optional).

y_var

A variable in x that contains observations. Specified as the argument varin dplyr::pull().

...

Unused.

y

A numeric vector of observations. If supplied, overrides y_var. Otherwise, defaults to dplyr::pull(x, y_var).

concave

A boolean value indicating whether to calculate the concave hull or the raw ROC diagnostic.

r

A reference triptych_mcbdsc object whose attributes are used for casting.

Value

A triptych_roc object, that is a vctrs_vctr subclass, and has a length equal to number of forecasting methods supplied in x. Each entry is named according to the corresponding forecasting method, and contains a list of named objects:

• estimate: A data frame of hit rates and false rates.

• region: Either an empty list, or a data frame of pointwise confidence intervals (along diagonal lines with slope -\pi_0/\pi_1) added by add_confidence().

• x: The numeric vector of original forecasts.

Access is most convenient through estimates(), regions(), and forecasts().

See Also

Accessors: estimates(), regions(), forecasts(), observations()

Adding uncertainty quantification: add_confidence()

Visualization: plot.triptych_roc(), autoplot.triptych_roc()

Examples

data(ex_binary, package = "triptych")

rc <- roc(ex_binary)
rc

# 1. Choose 4 predictions
# 2. Visualize
# 3. Adjust the title of the legend
rc[c(1, 3, 6, 9)] |>
  autoplot() +
  ggplot2::guides(colour = ggplot2::guide_legend("Forecast"))
  
# Build yourself using accessors
library(ggplot2)
df_est <- estimates(rc[c(1, 3, 6, 9)])
ggplot(df_est, aes(x = FAR, y = HR, col = forecast)) +
  geom_segment(aes(x = 0, y = 0, xend = 1, yend = 1)) +
  geom_path()