From 6c1d7a6703110c7b938c2e5a48392f9b856225af Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Thu, 5 Oct 2023 09:55:05 +1000
Subject: [PATCH] Use 0 when there are no relearning steps; ensure not NaN

---
 rslib/src/scheduler/fsrs/retention.rs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/rslib/src/scheduler/fsrs/retention.rs b/rslib/src/scheduler/fsrs/retention.rs
index b4b642654..359821a52 100644
--- a/rslib/src/scheduler/fsrs/retention.rs
+++ b/rslib/src/scheduler/fsrs/retention.rs
@@ -174,13 +174,12 @@ impl Collection {
             }
             let mut arr = [0.0; 5];
             for (review_kind, group) in group_sec_by_review_kind.iter().enumerate() {
-                let average_secs =
-                    if group.is_empty() && review_kind == RevlogReviewKind::Relearning as usize {
-                        30.0
-                    } else {
-                        group.iter().sum::<u32>() as f64 / group.len() as f64 / 1000.0
-                    };
-                arr[review_kind] = average_secs
+                let average_secs = group.iter().sum::<u32>() as f64 / group.len() as f64 / 1000.0;
+                arr[review_kind] = if average_secs.is_nan() {
+                    0.0
+                } else {
+                    average_secs
+                }
             }
             arr
         };