skip pareto-k check for low number of unique values

avehtari · avehtari · commit 7410b81bcec0 · 2025-10-17T20:44:16.000+03:00
diff --git a/R/loo_compare.R b/R/loo_compare.R
@@ -139,7 +139,7 @@ loo_compare.default <- function(x, ...) {
     # possible outliers in differences (Sivula et al., 2025;
     # Vehtari et al., 2024)
     khat_diff <- rep(NA, length(elpd_diff))
-    khat_diff[elpd_diff!=0] <- apply(diffs[,elpd_diff!=0, drop = FALSE], 2, \(x) posterior::pareto_khat(x, tail="both"))
+    khat_diff[elpd_diff!=0] <- apply(diffs[,elpd_diff!=0, drop = FALSE], 2, \(x) ifelse(length(unique(x))<=20, NA, posterior::pareto_khat(x, tail="both")))
     diag_pnorm[khat_diff > 0.5] <- paste0("khat_diff > 0.5")
   }
   rownames(comp) <- rnms

Original file line number	Diff line number	Diff line change
`@@ -139,7 +139,7 @@ loo_compare.default <- function(x, ...) {`
`139`	`139`	`# possible outliers in differences (Sivula et al., 2025;`
`140`	`140`	`# Vehtari et al., 2024)`
`141`	`141`	`khat_diff <- rep(NA, length(elpd_diff))`
`142`		`- khat_diff[elpd_diff!=0] <- apply(diffs[,elpd_diff!=0, drop = FALSE], 2, \(x) posterior::pareto_khat(x, tail="both"))`
	`142`	`+ khat_diff[elpd_diff!=0] <- apply(diffs[,elpd_diff!=0, drop = FALSE], 2, \(x) ifelse(length(unique(x))<=20, NA, posterior::pareto_khat(x, tail="both")))`
`143`	`143`	`diag_pnorm[khat_diff > 0.5] <- paste0("khat_diff > 0.5")`
`144`	`144`	`}`
`145`	`145`	`rownames(comp) <- rnms`