[jmgirard]

.visualization_recipe() merged the facet argument into the facet_grid layer instead of grid. The facet grid is used for four or more by variables. So grid = list(scales = "free") failed with is.list(val) is not TRUE when facet was not set, and when both were set, facet changed the grid layer and grid was ignored.

data <- iris
data$fac <- rep_len(c("A", "B"), 150)
data$fac2 <- rep_len(c("X", "X", "X", "Y", "Y", "Y"), 150)
m <- lm(Sepal.Length ~ Species * fac * Sepal.Width * fac2, data = data)
x <- estimate_relation(m, by = c("Species", "Sepal.Width", "fac", "fac2"))

plot(x, grid = list(scales = "free"))  # previously: Error in utils::modifyList(): is.list(val) is not TRUE

Changes

• .visualization_recipe() (R/visualisation_recipe_internal.R): the facet_grid layer is modified with grid, not facet.
• Tests (tests/testthat/test-visualisation_recipe.R): the default scales = "free_x", grid applied to the layer, and facet leaving the layer unchanged.
• NEWS entry and version bump to 0.17.0.16.

[Copilot]

🟢 Approval recommended

The reviewed changes address the reported issue with regression coverage and documentation updates.

0 open findings

What changed in this PR

Fixes grid handling for facet_grid layers in visualization recipes with four or more grouping variables.

Changes:

• Applies grid customization to facet_grid.
• Adds regression tests for defaults and argument interaction.
• Updates NEWS and the development version.

File	Description
tests/​testthat/​test-visualisation_recipe.R	Adds regression coverage.
R/​visualisation_recipe_internal.R	Corrects grid customization.
NEWS.md	Documents the fix.
DESCRIPTION	Bumps the development version.

🧠 Review effort: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.