From d5a026455eebba68432339e6dcb8c4b8acecf4a9 Mon Sep 17 00:00:00 2001
From: Luke Manley <lukemanley@gmail.com>
Date: Tue, 26 Nov 2024 19:06:25 -0500
Subject: [PATCH 1/2] fix: regression in `hist` panicking

---
 crates/polars-ops/src/chunked_array/hist.rs  | 14 ++++----------
 py-polars/tests/unit/operations/test_hist.py | 13 +++++++++++++
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/crates/polars-ops/src/chunked_array/hist.rs b/crates/polars-ops/src/chunked_array/hist.rs
index 16ae776cae4a..87dc77429386 100644
--- a/crates/polars-ops/src/chunked_array/hist.rs
+++ b/crates/polars-ops/src/chunked_array/hist.rs
@@ -93,7 +93,6 @@ where
     let min_break: f64 = breaks[0];
     let max_break: f64 = breaks[num_bins];
     let width = breaks[1] - min_break; // guaranteed at least one bin
-    let is_integer = !T::get_dtype().is_float();
 
     for chunk in ca.downcast_iter() {
         for item in chunk.non_null_values_iter() {
@@ -101,15 +100,10 @@ where
             if include_lower && item == min_break {
                 count[0] += 1;
             } else if item > min_break && item <= max_break {
-                let idx = (item - min_break) / width;
-                // This is needed for numeric stability for integers.
-                // We can fall directly on a boundary with an integer.
-                let idx = if is_integer && (idx.round() - idx).abs() < 0.0000001 {
-                    idx.round() - 1.0
-                } else {
-                    idx.ceil() - 1.0
-                };
-                count[idx as usize] += 1;
+                let idx = ((item - min_break) / width).floor() as usize;
+                // handle the case where item lands on the max_break boundary
+                let idx = if idx == num_bins { idx - 1 } else { idx };
+                count[idx] += 1;
             }
         }
     }
diff --git a/py-polars/tests/unit/operations/test_hist.py b/py-polars/tests/unit/operations/test_hist.py
index f3f52e2cfa92..eec0dd263b7f 100644
--- a/py-polars/tests/unit/operations/test_hist.py
+++ b/py-polars/tests/unit/operations/test_hist.py
@@ -410,3 +410,16 @@ def test_hist_floating_point() -> None:
         upper = bp[i]
 
         assert ((s <= upper) & (s > lower)).sum() == count[i]
+
+
+def test_hist_max_boundary_19998() -> None:
+    s = pl.Series(
+        [
+            9514.988509739183,
+            30738.098872148617,
+            41400.15705103004,
+            49093.06982022727,
+        ]
+    )
+    result = s.hist(bin_count=50)
+    assert result["count"].sum() == 4

From 5d9595d2197f12aba9658a9e1a3600c392a7a8f4 Mon Sep 17 00:00:00 2001
From: Luke Manley <lukemanley@gmail.com>
Date: Tue, 26 Nov 2024 20:29:25 -0500
Subject: [PATCH 2/2] fix

---
 crates/polars-ops/src/chunked_array/hist.rs | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/crates/polars-ops/src/chunked_array/hist.rs b/crates/polars-ops/src/chunked_array/hist.rs
index 87dc77429386..27ab0df27798 100644
--- a/crates/polars-ops/src/chunked_array/hist.rs
+++ b/crates/polars-ops/src/chunked_array/hist.rs
@@ -99,11 +99,18 @@ where
             let item = item.to_f64().unwrap();
             if include_lower && item == min_break {
                 count[0] += 1;
-            } else if item > min_break && item <= max_break {
-                let idx = ((item - min_break) / width).floor() as usize;
-                // handle the case where item lands on the max_break boundary
-                let idx = if idx == num_bins { idx - 1 } else { idx };
-                count[idx] += 1;
+            } else if item == max_break {
+                count[num_bins - 1] += 1;
+            } else if item > min_break && item < max_break {
+                let width_multiple = (item - min_break) / width;
+                let idx = width_multiple.floor();
+                // handle the case where item lands on the boundary
+                let idx = if idx == width_multiple {
+                    idx - 1.0
+                } else {
+                    idx
+                };
+                count[idx as usize] += 1;
             }
         }
     }