bug fix: coloring for numeric columns

 - While updating the vignette, I noticed that the size_by and color_by arguments occasionally didnt line up for numeric columns. Numeric columns need to be sorted first so the right colors are assigned. This was previously "tested" using the character 'run' column, though was more observable when testing against objective function values (which dont necessarily appear in ascending/descending order)

R/model-tree.R

@@ -680,7 +680,19 @@ color_tree_by <- function(tree_data, color_by = "run"){
     n_levels <- dplyr::n_distinct(vals)
 
     # To preview color palette: scales::show_col(pal_bbr)
-    if(inherits(vals, "logical")){
+    if(inherits(vals, "numeric")){
+      # Gradient coloring (sorted): get colors for unique values (excluding NA)
+      sorted_vals <- sort(unique(vals))
+      pal_bbr <- scales::pal_gradient_n(bbr_cols)(seq(0, 1, length.out = n_levels))
+
+      # Assign colors based on sorted values
+      color_mapping <- setNames(pal_bbr, sorted_vals)
+      tree_data$col <- ifelse(
+        tree_data$col %in% sorted_vals,
+        color_mapping[as.character(tree_data$col)],
+        tree_data$col
+      )
+    }else if(inherits(vals, "logical")){
       # Ensure both TRUE and FALSE colors are extracted, even if only one occurs
       pal_bbr <- scales::pal_gradient_n(bbr_cols)(c(0,1))
       # Explicitly set FALSE to white and TRUE to red
@@ -693,7 +705,7 @@ color_tree_by <- function(tree_data, color_by = "run"){
         )
       )
     }else{
-      # Gradient coloring: get colors for unique values (excluding NA)
+      # Gradient coloring; doesn't need to be sorted
       pal_bbr <- scales::pal_gradient_n(bbr_cols)(seq(0, 1, length.out = n_levels))
       tree_data$col <- factor(tree_data$col)
       levels(tree_data$col) <- c(node_colors, pal_bbr)