From 204591426625215255c1ddcf14fd66ed1a9b939e Mon Sep 17 00:00:00 2001
From: Evgenii Kuznetcov <evgenii.kuznetcov@appian.com>
Date: Mon, 18 Nov 2024 12:53:04 +0100
Subject: [PATCH] Return None/Null instead of 0 for empty input

---
 Cargo.lock         | 2 +-
 Cargo.toml         | 2 +-
 src/expressions.rs | 9 +++++++--
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 874871f..ae96916 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -947,7 +947,7 @@ dependencies = [
 
 [[package]]
 name = "polars-tdigest"
-version = "0.1.4"
+version = "0.1.5"
 dependencies = [
  "jemallocator",
  "ordered-float 4.2.0",
diff --git a/Cargo.toml b/Cargo.toml
index cbf83c0..a43f43d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "polars-tdigest"
-version = "0.1.4"
+version = "0.1.5"
 edition = "2021"
 
 [lib]
diff --git a/src/expressions.rs b/src/expressions.rs
index a405f9c..a7d2bf3 100644
--- a/src/expressions.rs
+++ b/src/expressions.rs
@@ -264,6 +264,11 @@ fn estimate_quantile(inputs: &[Series], kwargs: MergeTDKwargs) -> PolarsResult<S
 
     let tdigests: Vec<TDigest> = tdigest_json.into_iter().map(|td| td.tdigest).collect();
     let tdigest = TDigest::merge_digests(tdigests);
-    let ans = tdigest.estimate_quantile(kwargs.quantile);
-    Ok(Series::new("", vec![ans]))
+    if tdigest.is_empty() {
+        let v: &[Option<f64>] = &[None];
+        Ok(Series::new("", v))
+    } else {
+        let ans = tdigest.estimate_quantile(kwargs.quantile);
+        Ok(Series::new("", vec![ans]))
+    }
 }