include_reference = TRUE not working when using cut() directly in model formula

R/utils_format.R

@@ -371,13 +371,23 @@
 
   # check if we have model data, else return parameter table
   if (is.null(model_data)) {
-    params
+    return(params)
   }
 
   # find factors and factor levels and check if we have any factors in the data
   factors <- .find_factor_levels(model_data, model, model_call = attributes(params)$model_call)
   if (!length(factors)) {
-    params
+    # in case of "on-the-fly" factors, e.g.:
+    # m <- lm(mpg ~ cut(wt, c(0, 2.5, 3, 5)), data = mtcars)
+    # we need to receive the data from the model frame, in order to find factors
+    model_data <- insight::get_data(model, source = "mf", verbose = FALSE)
+    if (!is.null(model_data)) {
+      factors <- .find_factor_levels(model_data, model, model_call = attributes(params)$model_call)
+    }
+    # if we still didn't find anything, quit...
+    if (!length(factors)) {
+      return(params)
+    }
   }
 
   # we need some more information about prettified labels etc.
@@ -526,7 +536,7 @@
 
 # helper to format the header / subheader of different model components --------------
 
 .format_model_component_header <- function(x,
                                            type,
                                            split_column,
                                            is_zero_inflated,
@@ -895,7 +905,7 @@
 # or edge cases...
 
 #' @keywords internal
 .format_columns_multiple_components <- function(x,
                                                 pretty_names,
                                                 split_column = "Component",
                                                 digits = 2,

tests/testthat/test-pipe.R

@@ -13,3 +13,16 @@ test_that("print in pipe", {
     "Species [setosa]     |        0.00 |      |                |        |       "
   )
 })
+
+test_that("print in pipe, on-the-fly factor", {
+  data(mtcars)
+  out <- capture.output({
+    mtcars |>
+      lm(mpg ~ cut(wt, c(0, 2.5, 3, 5)), data = _) |>
+      model_parameters(include_reference = TRUE)
+  })
+  expect_identical(
+    out[4],
+    "cut(wt, c(0, 2.5, 3, 5)) [(0,2.5]] |        0.00 |      |                 |       |       "
+  )
+})