mbutrovich commented on code in PR #21522: URL: https://github.com/apache/datafusion/pull/21522#discussion_r3073714331
########## datafusion/functions-nested/src/array_compact.rs: ########## @@ -0,0 +1,191 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +//! [`ScalarUDFImpl`] definitions for array_compact function. + +use crate::utils::make_scalar_function; +use arrow::array::{ + Array, ArrayRef, Capacities, GenericListArray, MutableArrayData, OffsetSizeTrait, + make_array, +}; +use arrow::buffer::OffsetBuffer; +use arrow::datatypes::DataType; +use arrow::datatypes::DataType::{LargeList, List, Null}; +use datafusion_common::cast::{as_large_list_array, as_list_array}; +use datafusion_common::{Result, exec_err, utils::take_function_args}; +use datafusion_expr::{ + ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature, + Volatility, +}; +use datafusion_macros::user_doc; +use std::sync::Arc; + +make_udf_expr_and_func!( + ArrayCompact, + array_compact, + array, + "removes null values from the array.", + array_compact_udf +); + +#[user_doc( + doc_section(label = "Array Functions"), + description = "Removes null values from the array.", + syntax_example = "array_compact(array)", + sql_example = r#"```sql +> select array_compact([1, NULL, 2, NULL, 3]) arr; ++-----------+ +| arr | ++-----------+ +| [1, 2, 3] | ++-----------+ +```"#, + argument( + name = "array", + description = "Array expression. Can be a constant, column, or function, and any combination of array operators." + ) +)] +#[derive(Debug, PartialEq, Eq, Hash)] +pub struct ArrayCompact { + signature: Signature, + aliases: Vec<String>, +} + +impl Default for ArrayCompact { + fn default() -> Self { + Self::new() + } +} + +impl ArrayCompact { + pub fn new() -> Self { + Self { + signature: Signature::array(Volatility::Immutable), + aliases: vec!["list_compact".to_string()], + } + } +} + +impl ScalarUDFImpl for ArrayCompact { + fn name(&self) -> &str { + "array_compact" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> { + Ok(arg_types[0].clone()) + } + + fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { + make_scalar_function(array_compact_inner)(&args.args) + } + + fn aliases(&self) -> &[String] { + &self.aliases + } + + fn documentation(&self) -> Option<&Documentation> { + self.doc() + } +} + +/// array_compact SQL function +fn array_compact_inner(arg: &[ArrayRef]) -> Result<ArrayRef> { + let [input_array] = take_function_args("array_compact", arg)?; + + match &input_array.data_type() { + List(field) => { + let array = as_list_array(input_array)?; + compact_list::<i32>(array, field) + } + LargeList(field) => { + let array = as_large_list_array(input_array)?; + compact_list::<i64>(array, field) + } + Null => Ok(Arc::clone(input_array)), + array_type => exec_err!("array_compact does not support type '{array_type}'."), + } +} + +/// Remove null elements from each row of a list array. +fn compact_list<O: OffsetSizeTrait>( + list_array: &GenericListArray<O>, + field: &Arc<arrow::datatypes::Field>, +) -> Result<ArrayRef> { + let values = list_array.values(); + + // Fast path: no nulls in values, return input unchanged + if values.null_count() == 0 { + return Ok(Arc::new(list_array.clone())); + } + + let original_data = values.to_data(); + let capacity = original_data.len() - values.null_count(); + let mut offsets = Vec::<O>::with_capacity(list_array.len() + 1); + offsets.push(O::zero()); + let mut mutable = MutableArrayData::with_capacities( + vec![&original_data], + false, + Capacities::Array(capacity), + ); + + for row_index in 0..list_array.len() { Review Comment: ```rust let nulls = list_array.nulls(); for row_index in 0..list_array.len() { if nulls.is_some_and(|n| n.is_null(row_index)) { offsets.push(offsets[row_index]); continue; } ``` would make it consistent with behavior in https://github.com/apache/datafusion/pull/21482 and https://github.com/apache/datafusion/pull/21532 -- This is an automated message from the Apache Git Service. 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