R/example/example_categorical.R

In SHAPforxgboost: SHAP Plots for 'XGBoost'

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#
# use `var_cat` to add a categorical variable, output the long-format data differently:
library("data.table")
data("iris")
set.seed(123)
iris$Group <- 0
iris[sample(1:nrow(iris), nrow(iris)/2), "Group"] <- 1

data.table::setDT(iris)
X_train = as.matrix(iris[,c(colnames(iris)[1:4], "Group"), with = FALSE])
mod1 = xgboost::xgboost(
  data = X_train, label = iris$Species, gamma = 0, eta = 1,
  lambda = 0, nrounds = 1, verbose = FALSE, nthread = 1)

shap_long2 <- shap.prep(xgb_model = mod1, X_train = X_train, var_cat = "Group")
# **SHAP summary plot**
shap.plot.summary(shap_long2, scientific = TRUE) +
  ggplot2::facet_wrap(~ Group)