estimate_slopes() column naming breaks plotting brms (#530)

* estimate_slopes() column naming breaks plotting brms
Fixes #529

* news, desc

* fix

* add test

Author: strengejacke

DESCRIPTION

@@ -1,7 +1,7 @@
 Type: Package
 Package: modelbased
 Title: Estimation of Model-Based Predictions, Contrasts and Means
-Version: 0.11.2.15
+Version: 0.11.2.16
 Authors@R:
     c(person(given = "Dominique",
              family = "Makowski",

NEWS.md

@@ -37,6 +37,9 @@
 
 * Fixed issues with object of class `aov`.
 
+* Fixed issue with the `plot()` method for `estimate_slopes()` for Bayesian
+  models.
+
 # modelbased 0.11.2
 
 ## Changes

R/visualisation_recipe_internal.R

@@ -55,7 +55,15 @@
   } else if ("estimate_means" %in% att$class) {
     aes$y <- att$coef_name
   } else if ("estimate_slopes" %in% att$class) {
-    aes$y <- "Slope"
+    # for frequentist models, we have "Slope" as column name, for Bayesian models
+    # we have "Median", "Mean" or "MAP"
+    valid_y_vars <- intersect(c("Slope", "Median", "Mean", "MAP"), colnames(data))
+    # we wouldn't expect that there is more than one of these columns, but we
+    # check for that anyway...
+    if (length(valid_y_vars) == 0) {
+      insight::format_error("Could not find a suitable column for the y-axis. Expected one of: 'Slope', 'Median', 'Mean', 'MAP'.")
+    }
+    aes$y <- valid_y_vars[1]
     if ("Comparison" %in% names(data)) {
       # Insert "Comparison" column as the 2nd by so that it gets plotted as color
       if (length(by) > 1) {

tests/testthat/_snaps/plot-slopes/plot-slopes-brms-1.svg

@@ -168,7 +168,7 @@ test_that("estimate_slopes, works with glmmTMB", {
 })
 
 
-test_that("estimate_slopes, works with glmmTMB", {
+test_that("estimate_slopes, works with glmmTMB and splines", {
   skip_if_not_installed("mgcv")
   data(iris)
   model <- mgcv::gam(Sepal.Width ~ s(Petal.Length, by = Species), data = iris)

tests/testthat/test-estimate_slopes.R

@@ -24,3 +24,23 @@ test_that("plot slopes, correct y axis labels", {
     plot(slopes)
   )
 })
+
+
+test_that("estimate_slopes, plotting works with brms", {
+  skip_if_not_installed("brms")
+  skip_if_not_installed("BH")
+  skip_if_not_installed("RcppEigen")
+  skip_if_not_installed("curl")
+  skip_if_offline()
+  skip_if_not_installed("httr2")
+
+  m <- insight::download_model("brms_slopes_1")
+  skip_if(is.null(m))
+
+  set.seed(123)
+  out <- estimate_slopes(m, "Murder", by = "Illiteracy", length = 4)
+  vdiffr::expect_doppelganger(
+    "plot-slopes-brms-1",
+    plot(out)
+  )
+})