feat: Support list group-by of non numeric lists

crates/polars-arrow/src/legacy/kernels/mod.rs

@@ -10,7 +10,6 @@ pub mod fixed_size_list;
 pub mod float;
 #[cfg(feature = "compute_take")]
 pub mod list;
-pub mod list_bytes_iter;
 pub mod pow;
 pub mod rolling;
 pub mod set;

crates/polars-core/src/frame/group_by/into_groups.rs

@@ -1,10 +1,9 @@
-#[cfg(feature = "group_by_list")]
-use arrow::legacy::kernels::list_bytes_iter::numeric_list_bytes_iter;
 use arrow::legacy::kernels::sort_partition::{create_clean_partitions, partition_to_groups};
 use polars_utils::total_ord::{ToTotalOrd, TotalHash};
 
 use super::*;
 use crate::config::verbose;
+use crate::prelude::sort::arg_sort_multiple::_get_rows_encoded_ca_unordered;
 use crate::utils::_split_offsets;
 use crate::utils::flatten::flatten_par;
 
@@ -368,63 +367,14 @@ impl IntoGroupsProxy for ListChunked {
     #[allow(clippy::needless_lifetimes)]
     #[allow(unused_variables)]
     fn group_tuples<'a>(&'a self, multithreaded: bool, sorted: bool) -> PolarsResult<GroupsProxy> {
-        #[cfg(feature = "group_by_list")]
-        {
-            polars_ensure!(
-                self.inner_dtype().to_physical().is_numeric(),
-                ComputeError: "grouping on list type is only allowed if the inner type is numeric"
-            );
-
-            let hb = RandomState::default();
-            let null_h = get_null_hash_value(&hb);
-
-            let arr_to_hashes = |ca: &ListChunked| {
-                let mut out = Vec::with_capacity(ca.len());
-
-                for arr in ca.downcast_iter() {
-                    out.extend(numeric_list_bytes_iter(arr)?.map(|opt_bytes| {
-                        let hash = match opt_bytes {
-                            Some(s) => hb.hash_one(s),
-                            None => null_h,
-                        };
-
-                        // SAFETY:
-                        // the underlying data is tied to self
-                        unsafe {
-                            std::mem::transmute::<BytesHash<'_>, BytesHash<'a>>(BytesHash::new(
-                                opt_bytes, hash,
-                            ))
-                        }
-                    }))
-                }
-                Ok(out)
-            };
+        let by = &[self.clone().into_series()];
+        let ca = if multithreaded {
+            encode_rows_vertical_par_unordered(by).unwrap()
+        } else {
+            _get_rows_encoded_ca_unordered("", by).unwrap()
+        };
 
-            if multithreaded {
-                let n_partitions = _set_partition_size();
-                let split = _split_offsets(self.len(), n_partitions);
-
-                let groups: PolarsResult<_> = POOL.install(|| {
-                    let bytes_hashes = split
-                        .into_par_iter()
-                        .map(|(offset, len)| {
-                            let ca = self.slice(offset as i64, len);
-                            arr_to_hashes(&ca)
-                        })
-                        .collect::<PolarsResult<Vec<_>>>()?;
-                    let bytes_hashes = bytes_hashes.iter().collect::<Vec<_>>();
-                    Ok(group_by_threaded_slice(bytes_hashes, n_partitions, sorted))
-                });
-                groups
-            } else {
-                let hashes = arr_to_hashes(self)?;
-                Ok(group_by(hashes.iter(), sorted))
-            }
-        }
-        #[cfg(not(feature = "group_by_list"))]
-        {
-            panic!("activate 'group_by_list' feature")
-        }
+        ca.group_tuples(multithreaded, sorted)
     }
 }
 

crates/polars-core/src/hashing/vector_hasher.rs

@@ -1,6 +1,4 @@
 use arrow::bitmap::utils::get_bit_unchecked;
-#[cfg(feature = "group_by_list")]
-use arrow::legacy::kernels::list_bytes_iter::numeric_list_bytes_iter;
 use polars_utils::total_ord::{ToTotalOrd, TotalHash};
 use rayon::prelude::*;
 use xxhash_rust::xxh3::xxh3_64_with_seed;
@@ -379,58 +377,6 @@ impl VecHash for BooleanChunked {
     }
 }
 
-#[cfg(feature = "group_by_list")]
-impl VecHash for ListChunked {
-    fn vec_hash(&self, _random_state: RandomState, _buf: &mut Vec<u64>) -> PolarsResult<()> {
-        polars_ensure!(
-        self.inner_dtype().to_physical().is_numeric(),
-        ComputeError: "grouping on list type is only allowed if the inner type is numeric"
-        );
-        _buf.clear();
-        _buf.reserve(self.len());
-        let null_h = get_null_hash_value(&_random_state);
-
-        for arr in self.downcast_iter() {
-            _buf.extend(
-                numeric_list_bytes_iter(arr)?.map(|opt_bytes| match opt_bytes {
-                    Some(s) => xxh3_64_with_seed(s, null_h),
-                    None => null_h,
-                }),
-            )
-        }
-        Ok(())
-    }
-
-    fn vec_hash_combine(
-        &self,
-        _random_state: RandomState,
-        _hashes: &mut [u64],
-    ) -> PolarsResult<()> {
-        polars_ensure!(
-        self.inner_dtype().to_physical().is_numeric(),
-        ComputeError: "grouping on list type is only allowed if the inner type is numeric"
-        );
-
-        let null_h = get_null_hash_value(&_random_state);
-
-        let mut offset = 0;
-        self.downcast_iter().try_for_each(|arr| {
-            numeric_list_bytes_iter(arr)?
-                .zip(&mut _hashes[offset..])
-                .for_each(|(opt_bytes, h)| {
-                    let l = match opt_bytes {
-                        Some(s) => xxh3_64_with_seed(s, null_h),
-                        None => null_h,
-                    };
-                    *h = _boost_hash_combine(l, *h)
-                });
-            offset += arr.len();
-            PolarsResult::Ok(())
-        })?;
-        Ok(())
-    }
-}
-
 #[cfg(feature = "object")]
 impl<T> VecHash for ObjectChunked<T>
 where

crates/polars-core/src/series/implementations/list.rs

@@ -44,22 +44,6 @@ impl private::PrivateSeries for SeriesWrap<ListChunked> {
         IntoGroupsProxy::group_tuples(&self.0, multithreaded, sorted)
     }
 
-    #[cfg(feature = "group_by_list")]
-    fn vec_hash(&self, _build_hasher: RandomState, _buf: &mut Vec<u64>) -> PolarsResult<()> {
-        self.0.vec_hash(_build_hasher, _buf)?;
-        Ok(())
-    }
-
-    #[cfg(feature = "group_by_list")]
-    fn vec_hash_combine(
-        &self,
-        _build_hasher: RandomState,
-        _hashes: &mut [u64],
-    ) -> PolarsResult<()> {
-        self.0.vec_hash_combine(_build_hasher, _hashes)?;
-        Ok(())
-    }
-
     fn into_total_eq_inner<'a>(&'a self) -> Box<dyn TotalEqInner + 'a> {
         (&self.0).into_total_eq_inner()
     }
@@ -154,7 +138,6 @@ impl SeriesTrait for SeriesWrap<ListChunked> {
         self.0.has_validity()
     }
 
-    #[cfg(feature = "group_by_list")]
     #[cfg(feature = "algorithm_group_by")]
     fn unique(&self) -> PolarsResult<Series> {
         if !self.inner_dtype().is_numeric() {
@@ -171,7 +154,6 @@ impl SeriesTrait for SeriesWrap<ListChunked> {
         Ok(unsafe { self.0.clone().into_series().agg_first(&groups?) })
     }
 
-    #[cfg(feature = "group_by_list")]
     #[cfg(feature = "algorithm_group_by")]
     fn n_unique(&self) -> PolarsResult<usize> {
         if !self.inner_dtype().is_numeric() {
@@ -189,7 +171,6 @@ impl SeriesTrait for SeriesWrap<ListChunked> {
         }
     }
 
-    #[cfg(feature = "group_by_list")]
     #[cfg(feature = "algorithm_group_by")]
     fn arg_unique(&self) -> PolarsResult<IdxCa> {
         if !self.inner_dtype().is_numeric() {

crates/polars-ops/Cargo.toml

@@ -103,7 +103,6 @@ extract_jsonpath = ["serde_json", "jsonpath_lib", "polars-json"]
 log = []
 hash = []
 reinterpret = ["polars-core/reinterpret"]
-group_by_list = ["polars-core/group_by_list"]
 rolling_window = ["polars-core/rolling_window"]
 moment = []
 mode = []

crates/polars-ops/src/series/ops/is_first_distinct.rs

@@ -88,7 +88,6 @@ fn is_first_distinct_struct(s: &Series) -> PolarsResult<BooleanChunked> {
     Ok(BooleanChunked::with_chunk(s.name(), arr))
 }
 
-#[cfg(feature = "group_by_list")]
 fn is_first_distinct_list(ca: &ListChunked) -> PolarsResult<BooleanChunked> {
     let groups = ca.group_tuples(true, false)?;
     let first = groups.take_group_firsts();
@@ -136,7 +135,6 @@ pub fn is_first_distinct(s: &Series) -> PolarsResult<BooleanChunked> {
         },
         #[cfg(feature = "dtype-struct")]
         Struct(_) => return is_first_distinct_struct(&s),
-        #[cfg(feature = "group_by_list")]
         List(inner) if inner.is_numeric() => {
             let ca = s.list().unwrap();
             return is_first_distinct_list(ca);

crates/polars-ops/src/series/ops/is_last_distinct.rs

@@ -40,7 +40,6 @@ pub fn is_last_distinct(s: &Series) -> PolarsResult<BooleanChunked> {
         },
         #[cfg(feature = "dtype-struct")]
         Struct(_) => return is_last_distinct_struct(&s),
-        #[cfg(feature = "group_by_list")]
         List(inner) if inner.is_numeric() => {
             let ca = s.list().unwrap();
             return is_last_distinct_list(ca);
@@ -157,7 +156,6 @@ fn is_last_distinct_struct(s: &Series) -> PolarsResult<BooleanChunked> {
     Ok(BooleanChunked::with_chunk(s.name(), arr))
 }
 
-#[cfg(feature = "group_by_list")]
 fn is_last_distinct_list(ca: &ListChunked) -> PolarsResult<BooleanChunked> {
     let groups = ca.group_tuples(true, false)?;
     // SAFETY: all groups have at least a single member

crates/polars/Cargo.toml

@@ -159,7 +159,6 @@ extract_jsonpath = [
 ]
 find_many = ["polars-plan/find_many"]
 fused = ["polars-ops/fused", "polars-lazy?/fused"]
-group_by_list = ["polars-core/group_by_list", "polars-ops/group_by_list"]
 interpolate = ["polars-ops/interpolate", "polars-lazy?/interpolate"]
 is_between = ["polars-lazy?/is_between", "polars-ops/is_between"]
 is_first_distinct = ["polars-lazy?/is_first_distinct", "polars-ops/is_first_distinct"]

crates/polars/src/lib.rs

@@ -225,7 +225,6 @@
 //!     - `asof_join` - Join ASOF, to join on nearest keys instead of exact equality match.
 //!     - `cross_join` - Create the Cartesian product of two [`DataFrame`]s.
 //!     - `semi_anti_join` - SEMI and ANTI joins.
-//!     - `group_by_list` - Allow group_by operation on keys of type List.
 //!     - `row_hash` - Utility to hash [`DataFrame`] rows to [`UInt64Chunked`]
 //!     - `diagonal_concat` - Concat diagonally thereby combining different schemas.
 //!     - `dataframe_arithmetic` - Arithmetic on ([`Dataframe`] and [`DataFrame`]s) and ([`DataFrame`] on [`Series`])

docs/user-guide/installation.md

@@ -125,7 +125,6 @@ The opt-in features are:
     - `join_asof` - Join ASOF, to join on nearest keys instead of exact equality match.
     - `cross_join` - Create the Cartesian product of two DataFrames.
     - `semi_anti_join` - SEMI and ANTI joins.
-    - `group_by_list` - Allow group by operation on keys of type List.
     - `row_hash` - Utility to hash DataFrame rows to UInt64Chunked
     - `diagonal_concat` - Concat diagonally thereby combining different schemas.
     - `dataframe_arithmetic` - Arithmetic on (Dataframe and DataFrames) and (DataFrame on Series)

py-polars/Cargo.toml

@@ -162,7 +162,6 @@ dtypes = [
   "dtype-i16",
   "dtype-u8",
   "dtype-u16",
-  "polars/group_by_list",
   "object",
 ]
 

py-polars/tests/unit/operations/test_join.py

@@ -815,3 +815,23 @@ def test_join_projection_invalid_name_contains_suffix_15243() -> None:
             .select(pl.col("b").filter(pl.col("b") == pl.col("foo_right")))
             .collect()
         )
+
+
+def test_join_list_non_numeric() -> None:
+    assert (
+        pl.DataFrame(
+            {
+                "lists": [
+                    ["a", "b", "c"],
+                    ["a", "c", "b"],
+                    ["a", "c", "b"],
+                    ["a", "c", "d"],
+                ]
+            }
+        )
+    ).group_by("lists", maintain_order=True).agg(pl.len().alias("count")).to_dict(
+        as_series=False
+    ) == {
+        "lists": [["a", "b", "c"], ["a", "c", "b"], ["a", "c", "d"]],
+        "count": [1, 2, 1],
+    }