Sort tail values

Author: VisruthSK

R/psis.R

@@ -213,7 +213,7 @@ do_psis_i <- function(log_ratios_i, tail_len_i, ...) {
   # shift log ratios for safer exponentation
   lw_i <- log_ratios_i - max(log_ratios_i)
 
-  if (length(unique(utils::tail(log_ratios_i, -tail_len_i))) == 1) {
+  if (length(unique(utils::tail(sort(log_ratios_i), tail_len_i))) == 1) {
     warning(
       "Can't fit generalized Pareto distribution ",
       "because all tail values are the same.",

tests/testthat/test_psis.R

@@ -150,4 +150,11 @@ test_that("do_psis_i throws warning if all tail values the same", {
     "all tail values are the same"
   )
   expect_equal(val$pareto_k, Inf)
+
+  xx <- c(4, 1, 4, 4, 4, 4, 4, 2, 3, 4, 4)
+  expect_warning(
+    val <- do_psis_i(xx, tail_len_i = 6),
+    "all tail values are the same"
+  )
+  expect_equal(val$pareto_k, Inf)
 })