From be3bb253515b1a56dd82d6566739c7af02f0dc8b Mon Sep 17 00:00:00 2001
From: Ritchie Vink <ritchie46@gmail.com>
Date: Mon, 12 Feb 2024 10:21:11 -0800
Subject: [PATCH] feat: apply negate in simplify expression pass (#14436)

---
 .../logical_plan/optimizer/simplify_expr.rs   | 27 +++++++++++++++++++
 py-polars/tests/unit/test_arity.py            | 22 +++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/crates/polars-plan/src/logical_plan/optimizer/simplify_expr.rs b/crates/polars-plan/src/logical_plan/optimizer/simplify_expr.rs
index c7de180a84ce..4776bf9f5993 100644
--- a/crates/polars-plan/src/logical_plan/optimizer/simplify_expr.rs
+++ b/crates/polars-plan/src/logical_plan/optimizer/simplify_expr.rs
@@ -229,12 +229,39 @@ impl OptimizationRule for SimplifyBooleanRule {
             {
                 Some(AExpr::Literal(LiteralValue::Boolean(true)))
             },
+            AExpr::Function {
+                input,
+                function: FunctionExpr::Negate,
+                ..
+            } if input.len() == 1 => {
+                let input = input[0];
+                let ae = expr_arena.get(input);
+                eval_negate(ae)
+            },
             _ => None,
         };
         Ok(out)
     }
 }
 
+fn eval_negate(ae: &AExpr) -> Option<AExpr> {
+    let out = match ae {
+        AExpr::Literal(lv) => match lv {
+            #[cfg(feature = "dtype-i8")]
+            LiteralValue::Int8(v) => LiteralValue::Int8(-*v),
+            #[cfg(feature = "dtype-i16")]
+            LiteralValue::Int16(v) => LiteralValue::Int16(-*v),
+            LiteralValue::Int32(v) => LiteralValue::Int32(-*v),
+            LiteralValue::Int64(v) => LiteralValue::Int64(-*v),
+            LiteralValue::Float32(v) => LiteralValue::Float32(-*v),
+            LiteralValue::Float64(v) => LiteralValue::Float64(-*v),
+            _ => return None,
+        },
+        _ => return None,
+    };
+    Some(AExpr::Literal(out))
+}
+
 fn eval_bitwise<F>(left: &AExpr, right: &AExpr, operation: F) -> Option<AExpr>
 where
     F: Fn(bool, bool) -> bool,
diff --git a/py-polars/tests/unit/test_arity.py b/py-polars/tests/unit/test_arity.py
index 4be2a1910fe9..ea62e6583cae 100644
--- a/py-polars/tests/unit/test_arity.py
+++ b/py-polars/tests/unit/test_arity.py
@@ -79,3 +79,25 @@ def test_broadcast_string_ops_12632(
     assert df.select(needs_broadcast.str.strip_chars(pl.col("name"))).height == 3
     assert df.select(needs_broadcast.str.strip_chars_start(pl.col("name"))).height == 3
     assert df.select(needs_broadcast.str.strip_chars_end(pl.col("name"))).height == 3
+
+
+def test_negate_inlined_14278() -> None:
+    df = pl.DataFrame(
+        {"group": ["A", "A", "B", "B", "B", "C", "C"], "value": [1, 2, 3, 4, 5, 6, 7]}
+    )
+
+    agg_expr = [
+        pl.struct("group", "value").tail(2).alias("list"),
+        pl.col("value").sort().tail(2).count().alias("count"),
+    ]
+
+    q = df.lazy().group_by("group").agg(agg_expr)
+    assert q.collect().sort("group").to_dict(as_series=False) == {
+        "group": ["A", "B", "C"],
+        "list": [
+            [{"group": "A", "value": 1}, {"group": "A", "value": 2}],
+            [{"group": "B", "value": 4}, {"group": "B", "value": 5}],
+            [{"group": "C", "value": 6}, {"group": "C", "value": 7}],
+        ],
+        "count": [2, 2, 2],
+    }