(datasketches-rust) 01/01: chore(tdigest): better handle Centroid adds

[ti...@apache.org]

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tison pushed a commit to branch floating-cal
in repository https://gitbox.apache.org/repos/asf/datasketches-rust.git

commit d77af8aca98e639965daa24dd54f3220b0f0d599
Author: tison <wa...@gmail.com>
AuthorDate: Tue Feb 10 21:17:00 2026 +0800

    chore(tdigest): better handle Centroid adds
    
    Signed-off-by: tison <wa...@gmail.com>
---
 datasketches/src/tdigest/sketch.rs | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/datasketches/src/tdigest/sketch.rs b/datasketches/src/tdigest/sketch.rs
index a790892..a9ef093 100644
--- a/datasketches/src/tdigest/sketch.rs
+++ b/datasketches/src/tdigest/sketch.rs
@@ -1251,15 +1251,24 @@ impl Centroid {
     fn add(&mut self, other: Centroid) {
         let (self_weight, other_weight) = (self.weight(), other.weight());
         let total_weight = self_weight + other_weight;
-        self.weight = self.weight.saturating_add(other.weight.get());
+        self.weight = self
+            .weight
+            .checked_add(other.weight.get())
+            .expect("weight overflow");
 
         let (self_mean, other_mean) = (self.mean, other.mean);
-        let ratio_self = self_weight / total_weight;
         let ratio_other = other_weight / total_weight;
-        self.mean = self_mean.mul_add(ratio_self, other_mean * ratio_other);
+        let delta = other_mean - self_mean;
+        self.mean = if delta.is_finite() {
+            delta.mul_add(ratio_other, self_mean)
+        } else {
+            let ratio_self = self_weight / total_weight;
+            self_mean.mul_add(ratio_self, other_mean * ratio_other)
+        };
+
         debug_assert!(
-            !self.mean.is_nan(),
-            "NaN values should never be present in centroids; self: {}, other: {}",
+            self.mean.is_finite(),
+            "Centroid's mean must be finite; self: {}, other: {}",
             self_mean,
             other_mean
         );


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