comphead commented on code in PR #17456: URL: https://github.com/apache/datafusion/pull/17456#discussion_r2328812074
########## datafusion/spark/src/function/map/map_from_arrays.rs: ########## @@ -0,0 +1,207 @@ +// 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. + +use std::any::Any; +use std::borrow::Cow; +use std::collections::HashSet; +use std::sync::Arc; + +use arrow::array::{Array, ArrayRef, AsArray, BooleanBuilder, MapArray, StructArray}; +use arrow::buffer::OffsetBuffer; +use arrow::compute::filter; +use arrow::datatypes::{DataType, Field, Fields}; +use datafusion_common::utils::take_function_args; +use datafusion_common::{exec_err, internal_err, Result, ScalarValue}; +use datafusion_expr::{ColumnarValue, ScalarUDFImpl, Signature, Volatility}; +use datafusion_functions::utils::make_scalar_function; + +#[derive(Debug, PartialEq, Eq, Hash)] +pub struct MapFromArrays { + signature: Signature, +} + +impl Default for MapFromArrays { + fn default() -> Self { + Self::new() + } +} + +impl MapFromArrays { + pub fn new() -> Self { + Self { + signature: Signature::any(2, Volatility::Immutable), + } + } +} + +impl ScalarUDFImpl for MapFromArrays { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "map_from_arrays" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> { + let [key_type, value_type] = take_function_args("map_from_arrays", arg_types)?; + Ok(return_type_from_key_value_types( + get_element_type(key_type)?, + get_element_type(value_type)?, + )) + } + + fn invoke_with_args( + &self, + args: datafusion_expr::ScalarFunctionArgs, + ) -> Result<ColumnarValue> { + make_scalar_function(map_from_arrays_inner, vec![])(&args.args) + } +} + +fn get_list_field(data_type: &DataType) -> Result<&Arc<Field>> { + match data_type { + DataType::List(element) + | DataType::LargeList(element) + | DataType::FixedSizeList(element, _) => Ok(element), + _ => exec_err!( + "map_from_arrays expects 2 listarrays for keys and values as arguments, got {data_type:?}" + ), + } +} + +fn get_element_type(data_type: &DataType) -> Result<&DataType> { + get_list_field(data_type).map(|field| field.data_type()) +} + +pub fn return_type_from_key_value_types( + key_type: &DataType, + value_type: &DataType, +) -> DataType { + DataType::Map( + Arc::new(Field::new( + "entries", + DataType::Struct(Fields::from(vec![ + // the key must not be nullable + Field::new("key", key_type.clone(), false), + Field::new("value", value_type.clone(), true), + ])), + false, // the entry is not nullable + )), + false, // the keys are not sorted + ) +} + +fn get_list_values(array: &ArrayRef) -> Result<&ArrayRef> { + match array.data_type() { + DataType::List(_) => Ok(array.as_list::<i32>().values()), + DataType::LargeList(_) => Ok(array.as_list::<i64>().values()), + DataType::FixedSizeList(..) => Ok(array.as_fixed_size_list().values()), + wrong_type => internal_err!( + "get_list_values expects List/LargeList/FixedSizeList as argument, got {wrong_type:?}" + ), + } +} + +fn map_from_arrays_inner(args: &[ArrayRef]) -> Result<ArrayRef> { + let [keys, values] = take_function_args("map_from_arrays", args)?; + + let flat_keys = get_list_values(keys)?; + let flat_values = get_list_values(values)?; + + let offsets: Cow<[i32]> = match keys.data_type() { + DataType::List(_) => Ok(Cow::Borrowed(keys.as_list::<i32>().offsets().as_ref())), + DataType::LargeList(_) => Ok(Cow::Owned( + keys.as_list::<i64>() + .offsets() + .iter() + .map(|i| *i as i32) + .collect::<Vec<_>>(), + )), + DataType::FixedSizeList(_, size) => Ok(Cow::Owned( + (0..=keys.len() as i32).map(|i| size * i).collect() + )), + wrong_type => internal_err!( + "map_from_arrays expects List/LargeList/FixedSizeList as first argument, got {wrong_type:?}" + ), + }?; + + map_from_keys_values_offsets(flat_keys, flat_values, &offsets) +} + +pub fn map_from_keys_values_offsets( + keys: &ArrayRef, + values: &ArrayRef, + offsets: &[i32], +) -> Result<ArrayRef> { + let (keys, values, offsets) = map_deduplicate_keys(keys, values, offsets)?; + + let fields = Fields::from(vec![ + Field::new("key", keys.data_type().clone(), false), + Field::new("value", values.data_type().clone(), true), + ]); + let entries = StructArray::try_new(fields.clone(), vec![keys, values], None)?; + let field = Arc::new(Field::new("entries", DataType::Struct(fields), false)); + Ok(Arc::new(MapArray::try_new( + field, offsets, entries, None, false, + )?)) +} + +pub fn map_deduplicate_keys( + keys: &ArrayRef, + values: &ArrayRef, + offsets: &[i32], +) -> Result<(ArrayRef, ArrayRef, OffsetBuffer<i32>)> { + let num_rows = offsets.len() - 1; + let mut new_offsets = Vec::with_capacity(num_rows + 1); + new_offsets.push(0); + let mut last_offset = 0; + + let mut needed_rows_builder = BooleanBuilder::new(); + for row_num in 0..num_rows { + let cur_offset = offsets[row_num] as usize; + let next_offset = offsets[row_num + 1] as usize; + let num_entries = next_offset - cur_offset; + let keys_slice = keys.slice(cur_offset, num_entries); + let mut seen_keys = HashSet::new(); Review Comment: I was thinking if we can avoid allocating `seen_keys` every row? My naive suggestion was to build arrays for the input ``` keys [0, 1, 2, 0] values ['a', 'b', 'c', 'd'] seen[1, 0, 0, 0] ``` and the filter keys/values by seen, WDYT would that work? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
