chore: add user message with link to loo-glossary in loo_compare outputx

Author: Florence Bockting

R/loo_compare.R

@@ -194,6 +194,17 @@ print.compare.loo <- function(x, ..., digits = 1, p_worse = TRUE) {
     )
   }
   print(x2, quote = FALSE, row.names = FALSE)
+
+  # show glossary for diagnostic flags
+  has_diag <- any(nzchar(x[["diag_diff"]], keepNA = FALSE), na.rm = TRUE) ||
+              any(nzchar(x[["diag_elpd"]], keepNA = FALSE), na.rm = TRUE)
+  if (has_diag && p_worse) {
+    message(
+      "\nDiagnostic flags present. ",
+      "See ?`loo-glossary` (sections `diag_diff` and `diag_elpd`) ",
+      "or https://mc-stan.org/loo/reference/loo-glossary.html."
+    )
+  }
   invisible(x)
 }
 

tests/testthat/_snaps/compare.md

@@ -47,6 +47,9 @@
         model elpd_diff se_diff p_worse diag_diff diag_elpd
        model1       0.0     0.0      NA                    
        model2      -4.1     0.1    1.00   N < 100          
+    Message
+      
+      Diagnostic flags present. See ?`loo-glossary` (sections `diag_diff` and `diag_elpd`) or https://mc-stan.org/loo/reference/loo-glossary.html.
 
 ---
 
@@ -84,6 +87,9 @@
        model1       0.0     0.0      NA                    
        model2      -4.1     0.1    1.00   N < 100          
        model3     -16.1     0.2    1.00   N < 100          
+    Message
+      
+      Diagnostic flags present. See ?`loo-glossary` (sections `diag_diff` and `diag_elpd`) or https://mc-stan.org/loo/reference/loo-glossary.html.
 
 # compare returns expected result (3 models)