Inverts the predicted probabilities in an ALE object to reflect complementary outcomes (i.e., 1 - p). This is particularly useful when the model probability predictions are opposite to what is desired for easy interpretability. With invert_probs(), there is no need to change the original data or retrain the model; the ALE data, p-values, and subsequent ALE plots will reflect the desired inverted probabilities.
Arguments
- ale_obj
An object of class
ALE.- rename_y_col
character(1). If provided, renames the y outcome column. When probabilities are inverted, the name of the outcome column often needs to change for more intuitive interpretability. The default
NULLdoes not change the outcome column name.- force
logical(1). If
TRUE, inverts probabilities even if they have already been inverted once before (reverting them). The defaultFALSEwill error if probabilities have already been inverted.
Details
This function inverts the ALE y-values (i.e., .y, .y_mean, .y_median, etc.) for all terms, including the main ALE effects, bootstrap data, and ALE statistics (aler_min, aler_max, etc.).
It also updates the y_col name and y_summary column names if rename_y_col is provided.
If the ALE object has already been inverted (probs_inverted = TRUE), the function throws an error by default.
To force reinversion (i.e., revert to original probabilities), set force = TRUE.
This operation is only permitted if the y-summary probabilities are all in the [0, 1] interval.
Examples
# \donttest{
# Binary model
setosa <- iris |>
dplyr::mutate(setosa = Species == "setosa") |>
dplyr::select(-Species)
ale_obj <- glm(setosa ~ ., data = setosa, family = binomial()) |>
ALE()
#> Warning: glm.fit: algorithm did not converge
#> Warning: glm.fit: fitted probabilities numerically 0 or 1 occurred
#> Warning: no non-missing arguments to max; returning -Inf
# Invert the predicted probabilities
ale_inverted <- invert_probs(ale_obj)
# Revert back to original by inverting again
ale_reverted <- invert_probs(ale_inverted, force = TRUE)
#> ! Probabilities are already inverted; they will now be reverted.
# }