From 80ece09f0d105fc22a32b35d534c7f2aeb693af9 Mon Sep 17 00:00:00 2001
From: Orson Peters <orsonpeters@gmail.com>
Date: Fri, 6 Sep 2024 18:51:08 +0200
Subject: [PATCH] refactor(rust): Fix nan-ignoring max/min in new-streaming

---
 crates/polars-core/src/datatypes/any_value.rs | 8 ++++++++
 crates/polars-core/src/scalar/mod.rs          | 5 +++++
 crates/polars-expr/src/reduce/min_max.rs      | 8 ++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/crates/polars-core/src/datatypes/any_value.rs b/crates/polars-core/src/datatypes/any_value.rs
index 5475b8fb5203..c3f5f57e0c68 100644
--- a/crates/polars-core/src/datatypes/any_value.rs
+++ b/crates/polars-core/src/datatypes/any_value.rs
@@ -499,6 +499,14 @@ impl<'a> AnyValue<'a> {
         )
     }
 
+    pub fn is_nan(&self) -> bool {
+        match self {
+            AnyValue::Float32(f) => f.is_nan(),
+            AnyValue::Float64(f) => f.is_nan(),
+            _ => false,
+        }
+    }
+
     pub fn is_null(&self) -> bool {
         matches!(self, AnyValue::Null)
     }
diff --git a/crates/polars-core/src/scalar/mod.rs b/crates/polars-core/src/scalar/mod.rs
index ed0ab1f98bfa..ac7a946ebebc 100644
--- a/crates/polars-core/src/scalar/mod.rs
+++ b/crates/polars-core/src/scalar/mod.rs
@@ -22,6 +22,11 @@ impl Scalar {
         self.value.is_null()
     }
 
+    #[inline(always)]
+    pub fn is_nan(&self) -> bool {
+        self.value.is_nan()
+    }
+
     #[inline(always)]
     pub fn value(&self) -> &AnyValue<'static> {
         &self.value
diff --git a/crates/polars-expr/src/reduce/min_max.rs b/crates/polars-expr/src/reduce/min_max.rs
index 5d514ce218c5..ba011d7d95f0 100644
--- a/crates/polars-expr/src/reduce/min_max.rs
+++ b/crates/polars-expr/src/reduce/min_max.rs
@@ -25,7 +25,9 @@ struct MinReduceState {
 
 impl MinReduceState {
     fn update_with_value(&mut self, other: &AnyValue<'static>) {
-        if self.value.is_null() || !other.is_null() && other < self.value.value() {
+        if self.value.is_null()
+            || !other.is_null() && (other < self.value.value() || self.value.is_nan())
+        {
             self.value.update(other.clone());
         }
     }
@@ -78,7 +80,9 @@ struct MaxReduceState {
 
 impl MaxReduceState {
     fn update_with_value(&mut self, other: &AnyValue<'static>) {
-        if self.value.is_null() || !other.is_null() && other > self.value.value() {
+        if self.value.is_null()
+            || !other.is_null() && (other > self.value.value() || self.value.is_nan())
+        {
             self.value.update(other.clone());
         }
     }