feat: add decision boundary plots

DESCRIPTION

@@ -63,14 +63,16 @@ Config/testthat/parallel: true
 Encoding: UTF-8
 NeedsCompilation: no
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.2.3
+RoxygenNote: 7.2.3.9000
 Collate:
     'BenchmarkResult.R'
     'Filter.R'
+    'LearnerClassif.R'
     'LearnerClassifCVGlmnet.R'
     'LearnerClassifGlmnet.R'
     'LearnerClassifRpart.R'
     'LearnerClustHierarchical.R'
+    'LearnerRegr.R'
     'LearnerRegrCVGlmnet.R'
     'LearnerRegrGlmnet.R'
     'LearnerRegrRpart.R'

NAMESPACE

@@ -5,13 +5,15 @@ S3method(as_precrec,PredictionClassif)
 S3method(as_precrec,ResampleResult)
 S3method(autoplot,BenchmarkResult)
 S3method(autoplot,Filter)
+S3method(autoplot,LearnerClassif)
 S3method(autoplot,LearnerClassifCVGlmnet)
 S3method(autoplot,LearnerClassifGlmnet)
 S3method(autoplot,LearnerClassifRpart)
 S3method(autoplot,LearnerClustAgnes)
 S3method(autoplot,LearnerClustDiana)
 S3method(autoplot,LearnerClustHclust)
 S3method(autoplot,LearnerClustHierarchical)
+S3method(autoplot,LearnerRegr)
 S3method(autoplot,LearnerRegrCVGlmnet)
 S3method(autoplot,LearnerRegrGlmnet)
 S3method(autoplot,LearnerRegrRpart)
@@ -52,6 +54,8 @@ import(checkmate)
 import(data.table)
 import(ggplot2)
 import(mlr3misc)
+importFrom(ggplot2,autoplot)
+importFrom(ggplot2,fortify)
 importFrom(graphics,plot)
 importFrom(scales,pretty_breaks)
 importFrom(stats,as.dendrogram)

R/LearnerClassif.R

@@ -0,0 +1,87 @@
+#' @title Plot for Classification Learners
+#'
+#' @description
+#' Visualizations for [mlr3::LearnerClassif].
+#' The argument `type` controls what kind of plot is drawn.
+#' Possible choices are:
+#'
+#' * `"prediction"` (default): Decision boundary of the learner and the true class labels.
+#'
+#' @param object ([mlr3::LearnerClassif]).
+#'
+#' @template param_type
+#' @template param_task
+#' @template param_grid_points
+#' @template param_expand_range
+#' @template param_theme
+#' @param ... (ignored).
+#'
+#' @return [ggplot2::ggplot()].
+#'
+#' @export
+#' @examples
+#' \donttest{
+#' if (requireNamespace("mlr3")) {
+#' library(mlr3)
+#' library(mlr3viz)
+#'
+#' task = tsk("pima")$select(c("age", "pedigree"))
+#' learner = lrn("classif.rpart", predict_type = "prob")
+#' learner$train(task)
+#'
+#' autoplot(learner, type = "prediction", task)
+#' }
+#' }
+autoplot.LearnerClassif = function(object, type = "prediction", task, grid_points = 100L, expand_range = 0, theme = theme_minimal(), ...) { # nolint
+  assert_string(type)
+
+  switch(type,
+    "prediction" = {
+      mlr3::assert_task(task)
+      features = task$feature_names
+
+      if (length(features) != 2L) {
+        mlr3misc::stopf("Plot learner prediction only works for tasks with two features for classification!", wrap = TRUE)
+      }
+
+      grid = predict_grid(list(object), task, grid_points = 100L, expand_range = 0)
+
+      if (object$predict_type == "prob") {
+        # classif, probs
+        raster_aes = aes(
+          fill = .data[["response"]],
+          alpha = .data[[".prob.response"]])
+        scale_alpha = scale_alpha_continuous(
+          name = "Probability",
+          guide = guide_legend(override.aes = list(fill = viridis::viridis(1))))
+        scale_fill = scale_fill_viridis_d(end = 0.8)
+        guides = NULL
+      } else if (object$predict_type == "response") {
+        # classif, no probs
+        raster_aes = aes(fill = .data[["response"]])
+        scale_alpha = NULL
+        scale_fill = scale_fill_viridis_d(end = 0.8)
+        guides = NULL
+      }
+
+      ggplot(grid,
+        mapping = aes(
+          x = .data[[features[1L]]],
+          y = .data[[features[2L]]])) +
+        geom_raster(raster_aes) +
+        geom_point(
+          mapping = aes(fill = .data[[task$target_names]]),
+          data = task$data(),
+          shape = 21,
+          color = "black") +
+        scale_fill +
+        guides +
+        theme +
+        theme(legend.position = "right") +
+        scale_alpha +
+        labs(fill = "Response")
+    },
+
+    stopf("Unknown plot type '%s'", type)
+  )
+}

R/LearnerClassifCVGlmnet.R

@@ -1,10 +1,19 @@
 #' @rdname autoplot.LearnerClassifGlmnet
 #' @export
-autoplot.LearnerClassifCVGlmnet = function(object, theme = theme_minimal(), ...) { # nolint
-  plot_ggfortify(object, ...) +
-    scale_color_viridis_d("Feature") +
-    theme
+autoplot.LearnerClassifCVGlmnet = function(object, type = "prediction", task = NULL, grid_points = 100L, expand_range = 0, theme = theme_minimal(), ...) { # nolint
+  switch(type,
+    "prediction" = {
+      NextMethod()
+    },
 
+    "ggfortify" = {
+      plot_ggfortify(object, ...) +
+        scale_color_viridis_d("Feature") +
+        theme
+    },
+
+    stopf("Unknown plot type '%s'", type)
+  )
 }
 
 #' @export

R/LearnerClassifGlmnet.R

@@ -1,9 +1,19 @@
 #' @title Plots for GLMNet Learners
 #'
 #' @description
-#' Visualizations for GLMNet learners using the package \CRANpkg{ggfortify}.
+#' Visualizations for [mlr3learners::LearnerClassifGlmnet].
+#' The argument `type` controls what kind of plot is drawn.
+#' Possible choices are:
+#'
+#' * `"prediction"` (default): Decision boundary of the learner and the true class labels.
+#' * `"ggfortify"`: Visualizes the model using the package \CRANpkg{ggfortify}.
 #'
 #' @param object ([mlr3learners::LearnerClassifGlmnet] | [mlr3learners::LearnerRegrGlmnet] | [mlr3learners::LearnerRegrCVGlmnet] | [mlr3learners::LearnerRegrCVGlmnet]).
+#'
+#' @template param_type
+#' @template param_task
+#' @template param_grid_points
+#' @template param_expand_range
 #' @template param_theme
 #' @param ... (ignored).
 #'
@@ -23,22 +33,34 @@
 #' task = tsk("sonar")
 #' learner = lrn("classif.glmnet")
 #' learner$train(task)
-#' autoplot(learner)
+#' autoplot(learner, type = "ggfortify")
 #'
 #' # regression
 #' task = tsk("mtcars")
 #' learner = lrn("regr.glmnet")
 #' learner$train(task)
-#' autoplot(learner)
+#' autoplot(learner, type = "ggfortify")
 #' }
-autoplot.LearnerClassifGlmnet = function(object, theme = theme_minimal(), ...) { # nolint
-  if ("twoclass" %nin% object$state$train_task$properties) {
-    stopf("Plot of %s only works with binary classification tasks.", object$id)
-  }
+autoplot.LearnerClassifGlmnet = function(object, type = "prediction", task = NULL, grid_points = 100L, expand_range = 0, theme = theme_minimal(), ...) { # nolint
+  assert_has_model(object)
+
+  switch(type,
+    "prediction" = {
+      NextMethod()
+    },
+
+    "ggfortify" = {
+      if ("twoclass" %nin% object$state$train_task$properties) {
+        stopf("Plot of %s only works with binary classification tasks.", object$id)
+      }
+
+      plot_ggfortify(object) +
+        scale_color_viridis_d("Feature") +
+        theme
+    },
 
-  plot_ggfortify(object) +
-      scale_color_viridis_d("Feature") +
-      theme
+    stopf("Unknown plot type '%s'", type)
+  )
 }
 
 #' @export

R/LearnerClassifRpart.R

@@ -1,9 +1,19 @@
 #' @title Plots for Rpart Learners
 #'
 #' @description
-#' Visualizations rpart trees using the package \CRANpkg{ggparty}.
+#' Visualizations for [mlr3::LearnerClassifRpart].
+#' The argument `type` controls what kind of plot is drawn.
+#' Possible choices are:
+#'
+#' * `"prediction"` (default): Decision boundary of the learner and the true class labels.
+#' * `"ggparty"`: Visualizes the tree using the package \CRANpkg{ggparty}.
 #'
 #' @param object ([mlr3::LearnerClassifRpart] | [mlr3::LearnerRegrRpart]).
+#'
+#' @template param_type
+#' @template param_task
+#' @template param_grid_points
+#' @template param_expand_range
 #' @template param_theme
 #' @param ... (ignored).
 #'
@@ -19,45 +29,50 @@
 #'   task = tsk("iris")
 #'   learner = lrn("classif.rpart", keep_model = TRUE)
 #'   learner$train(task)
-#'   autoplot(learner)
+#'   autoplot(learner, type = "ggparty")
 #'
 #'   # regression
 #'   task = tsk("mtcars")
 #'   learner = lrn("regr.rpart", keep_model = TRUE)
 #'   learner$train(task)
-#'   autoplot(learner)
+#'   autoplot(learner, type = "ggparty")
 #' }
-autoplot.LearnerClassifRpart = function(object, theme = theme_minimal(), ...) { # nolint
+autoplot.LearnerClassifRpart = function(object, type = "prediction", task = NULL, grid_points = 100L, expand_range = 0, theme = theme_minimal(), ...) { # nolint
   assert_has_model(object)
 
-  if (is.null(object$model$model)) {
-    stopf("Learner '%s' must be trained with `keep_model` set to `TRUE`", object$id)
-  }
+  switch(type,
+    "prediction" = {
+      NextMethod()
+    },
+
+    "ggparty" = {
+      require_namespaces(c("partykit", "ggparty"))
+      target = all.vars(object$model$terms)[1L]
 
-  require_namespaces(c("partykit", "ggparty"))
-  target = all.vars(object$model$terms)[1L]
+      ggparty::ggparty(partykit::as.party(object$model)) +
+        ggparty::geom_edge() +
+        ggparty::geom_edge_label() +
+        ggparty::geom_node_splitvar() +
+        ggparty::geom_node_plot(
+          gglist = list(
+            geom_bar(aes(x = "", fill = .data[[target]]),
+            alpha = 0.8,
+            color = "#000000",
+            linewidth = 0.5,
+            position = position_fill()),
+            xlab(target),
+            scale_fill_viridis_d(end = 0.8),
+            theme),
+          ids = "terminal",
+          shared_axis_labels= TRUE) +
+        ggparty::geom_node_label(
+          mapping = aes(label = paste0("n=", .data[["nodesize"]])),
+          nudge_y = 0.03,
+          ids = "terminal")
+    },
 
-  ggparty::ggparty(partykit::as.party(object$model)) +
-    ggparty::geom_edge() +
-    ggparty::geom_edge_label() +
-    ggparty::geom_node_splitvar() +
-    ggparty::geom_node_plot(
-      gglist = list(
-        geom_bar(aes(x = "", fill = .data[[target]]),
-        alpha = 0.8,
-        color = "#000000",
-        linewidth = 0.5,
-        position = position_fill()),
-        xlab(target),
-        scale_fill_viridis_d(end = 0.8),
-        theme),
-      ids = "terminal",
-      shared_axis_labels= TRUE) +
-    ggparty::geom_node_label(
-      mapping = aes(label = paste0("n=", .data[["nodesize"]])),
-      nudge_y = 0.03,
-      ids = "terminal"
-    )
+    stopf("Unknown plot type '%s'", type)
+  )
 }
 
 #' @export