sv_dependence: SHAP Dependence Plot

Description

Scatterplot of the SHAP values of a feature against its feature values. If SHAP interaction values are available, setting interactions = TRUE allows to focus on pure interaction effects (multiplied by two) or on pure main effects. By default, the feature on the color scale is selected via SHAP interactions (if available) or an interaction heuristic, see potential_interactions().

Usage

sv_dependence(object, ...)
# S3 method for default
sv_dependence(object, ...)
# S3 method for shapviz
sv_dependence(
  object,
  v,
  color_var = "auto",
  color = "#3b528b",
  viridis_args = getOption("shapviz.viridis_args"),
  jitter_width = NULL,
  interactions = FALSE,
  ih_nbins = NULL,
  ih_color_num = TRUE,
  ih_scale = FALSE,
  ih_adjusted = FALSE,
  ...
)
# S3 method for mshapviz
sv_dependence(
  object,
  v,
  color_var = "auto",
  color = "#3b528b",
  viridis_args = getOption("shapviz.viridis_args"),
  jitter_width = NULL,
  interactions = FALSE,
  ih_nbins = NULL,
  ih_color_num = TRUE,
  ih_scale = FALSE,
  ih_adjusted = FALSE,
  ...
)

Value

An object of class "ggplot" (or "patchwork") representing a dependence plot.

Arguments

object: An object of class "(m)shapviz".
...: Arguments passed to ggplot2::geom_jitter().
v: Column name of feature to be plotted. Can be a vector/list if object is of class "shapviz".
color_var: Feature name to be used on the color scale to investigate interactions. The default ("auto") uses SHAP interaction values (if available), or a heuristic to select the strongest interacting feature. Set to NULL to not use the color axis. Can be a vector/list if object is of class "shapviz".
color: Color to be used if color_var = NULL. Can be a vector/list if v is a vector.
viridis_args: List of viridis color scale arguments, see ?ggplot2::scale_color_viridis_c. The default points to the global option shapviz.viridis_args, which corresponds to list(begin = 0.25, end = 0.85, option = "inferno"). These values are passed to ggplot2::scale_color_viridis_*(). For example, to switch to a standard viridis scale, you can either change the default via options(shapviz.viridis_args = list()), or set viridis_args = list(). Only relevant if color_var is not NULL.
jitter_width: The amount of horizontal jitter. The default (NULL) will use a value of 0.2 in case v is discrete, and no jitter otherwise. (Numeric variables are considered discrete if they have at most 7 unique values.) Can be a vector/list if v is a vector.
interactions: Should SHAP interaction values be plotted? Default is FALSE. Requires SHAP interaction values. If color_var = NULL (or it is equal to v), the pure main effect of v is visualized. Otherwise, twice the SHAP interaction values between v and the color_var are plotted.
ih_nbins, ih_color_num, ih_scale, ih_adjusted: Interaction heuristic (ih) parameters used to select the color variable, see potential_interactions(). Only used if color_var = "auto" and if there are no SHAP interaction values.

Methods (by class)

sv_dependence(default): Default method.
sv_dependence(shapviz): SHAP dependence plot for "shapviz" object.
sv_dependence(mshapviz): SHAP dependence plot for "mshapviz" object.

Examples

Run this code

dtrain <- xgboost::xgb.DMatrix(
  data.matrix(iris[, -1]), label = iris[, 1], nthread = 1
)
fit <- xgboost::xgb.train(data = dtrain, nrounds = 10, nthread = 1)
x <- shapviz(fit, X_pred = dtrain, X = iris)
sv_dependence(x, "Petal.Length")
sv_dependence(x, "Petal.Length", color_var = "Species")
sv_dependence(x, "Petal.Length", color_var = NULL)
sv_dependence(x, c("Species", "Petal.Length"))
sv_dependence(x, "Petal.Width", color_var = c("Species", "Petal.Length"))

# SHAP interaction values/main effects
x2 <- shapviz(fit, X_pred = dtrain, X = iris, interactions = TRUE)
sv_dependence(x2, "Petal.Length", interactions = TRUE)
sv_dependence(
  x2, c("Petal.Length", "Species"), color_var = NULL, interactions = TRUE
)