alamb commented on a change in pull request #9381: URL: https://github.com/apache/arrow/pull/9381#discussion_r570891227
########## File path: rust/arrow/src/compute/kernels/window.rs ########## @@ -0,0 +1,100 @@ +// 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. + +//! Defines windowing functions, like `shift`ing + +use crate::compute::concat; +use num::{abs, clamp}; +use std::sync::Arc; + +use crate::{ + array::{make_array, ArrayData, PrimitiveArray}, + datatypes::ArrowPrimitiveType, + error::Result, +}; +use crate::{ + array::{Array, ArrayRef}, + buffer::MutableBuffer, +}; + +/// Shifts array by defined number of items (to left or right) Review comment: I wonder if you can add a doc example here, something like https://github.com/apache/arrow/blob/master/rust/arrow/src/compute/kernels/take.rs#L62-L76 just to show the behavior (lifting / simplifying one of unit tests is probably a good level) ########## File path: rust/arrow/src/compute/kernels/window.rs ########## @@ -0,0 +1,100 @@ +// 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. + +//! Defines windowing functions, like `shift`ing + +use crate::compute::concat; +use num::{abs, clamp}; +use std::sync::Arc; + +use crate::{ + array::{make_array, ArrayData, PrimitiveArray}, + datatypes::ArrowPrimitiveType, + error::Result, +}; +use crate::{ + array::{Array, ArrayRef}, + buffer::MutableBuffer, +}; + +/// Shifts array by defined number of items (to left or right) +pub fn shift<T>(values: &PrimitiveArray<T>, offset: i64) -> Result<ArrayRef> +where + T: ArrowPrimitiveType, +{ + // Compute slice + let slice_offset = clamp(offset, 0, values.len() as i64) as usize; + let length = values.len() - abs(offset) as usize; + let slice = values.slice(slice_offset, length); + + // Generate array with remaining `null` items + let nulls = abs(offset as i64) as usize; + + let mut null_array = MutableBuffer::new(nulls); + let mut null_data = MutableBuffer::new(nulls * T::get_byte_width()); + null_array.extend_zeros(nulls); + null_data.extend_zeros(nulls * T::get_byte_width()); + + let null_data = ArrayData::new( + T::DATA_TYPE, + nulls as usize, + Some(nulls), + Some(null_array.into()), + 0, + vec![null_data.into()], + vec![], + ); + + // Concatenate both arrays, add nulls after if shift > 0 else before + let null_arr = make_array(Arc::new(null_data)); + if offset > 0 { + concat(&[slice.as_ref(), null_arr.as_ref()]) + } else { + concat(&[null_arr.as_ref(), slice.as_ref()]) + } +} + +#[cfg(test)] +mod tests { + use crate::array::Int32Array; + + use super::*; + + #[test] + fn test_shift_neg() { + let a: Int32Array = vec![Some(1), None, Some(4)].into(); + let res = shift(&a, -1).unwrap(); + + let b = res.as_any().downcast_ref::<Int32Array>().unwrap(); + assert_eq!(a.len(), res.len()); + assert_eq!(false, b.is_valid(0)); + assert_eq!(1, b.value(1)); + assert_eq!(false, b.is_valid(2)); Review comment: ```suggestion let expected: Int32Array = vec![None, Some(1), None].into(); assert_eq!(b, &expected); ``` ########## File path: rust/arrow/src/compute/kernels/window.rs ########## @@ -0,0 +1,100 @@ +// 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. + +//! Defines windowing functions, like `shift`ing + +use crate::compute::concat; +use num::{abs, clamp}; +use std::sync::Arc; + +use crate::{ + array::{make_array, ArrayData, PrimitiveArray}, + datatypes::ArrowPrimitiveType, + error::Result, +}; +use crate::{ + array::{Array, ArrayRef}, + buffer::MutableBuffer, +}; + +/// Shifts array by defined number of items (to left or right) Review comment: It might also be good to specify what happens if you shift by more than the size of the array (e.g. that there is no error, just the entire array is returned as null) ########## File path: rust/arrow/src/compute/kernels/window.rs ########## @@ -0,0 +1,100 @@ +// 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. + +//! Defines windowing functions, like `shift`ing + +use crate::compute::concat; +use num::{abs, clamp}; +use std::sync::Arc; + +use crate::{ + array::{make_array, ArrayData, PrimitiveArray}, + datatypes::ArrowPrimitiveType, + error::Result, +}; +use crate::{ + array::{Array, ArrayRef}, + buffer::MutableBuffer, +}; + +/// Shifts array by defined number of items (to left or right) +pub fn shift<T>(values: &PrimitiveArray<T>, offset: i64) -> Result<ArrayRef> +where + T: ArrowPrimitiveType, +{ + // Compute slice + let slice_offset = clamp(offset, 0, values.len() as i64) as usize; + let length = values.len() - abs(offset) as usize; + let slice = values.slice(slice_offset, length); + + // Generate array with remaining `null` items + let nulls = abs(offset as i64) as usize; + + let mut null_array = MutableBuffer::new(nulls); + let mut null_data = MutableBuffer::new(nulls * T::get_byte_width()); + null_array.extend_zeros(nulls); + null_data.extend_zeros(nulls * T::get_byte_width()); + + let null_data = ArrayData::new( + T::DATA_TYPE, + nulls as usize, + Some(nulls), + Some(null_array.into()), + 0, + vec![null_data.into()], + vec![], + ); + + // Concatenate both arrays, add nulls after if shift > 0 else before + let null_arr = make_array(Arc::new(null_data)); + if offset > 0 { + concat(&[slice.as_ref(), null_arr.as_ref()]) + } else { + concat(&[null_arr.as_ref(), slice.as_ref()]) + } +} + +#[cfg(test)] +mod tests { + use crate::array::Int32Array; + + use super::*; + + #[test] + fn test_shift_neg() { + let a: Int32Array = vec![Some(1), None, Some(4)].into(); + let res = shift(&a, -1).unwrap(); + + let b = res.as_any().downcast_ref::<Int32Array>().unwrap(); + assert_eq!(a.len(), res.len()); + assert_eq!(false, b.is_valid(0)); + assert_eq!(1, b.value(1)); + assert_eq!(false, b.is_valid(2)); + } + + #[test] + fn test_shift_pos() { + let a: Int32Array = vec![Some(1), None, Some(4)].into(); + let res = shift(&a, 1).unwrap(); + + let b = res.as_any().downcast_ref::<Int32Array>().unwrap(); + assert_eq!(a.len(), res.len()); + assert_eq!(false, b.is_valid(0)); + assert_eq!(4, b.value(1)); + assert_eq!(false, b.is_valid(2)); Review comment: ```suggestion let expected: Int32Array = vec![None, Some(1), None].into(); assert_eq!(b, &expected); ``` ########## File path: rust/arrow/src/compute/kernels/window.rs ########## @@ -0,0 +1,100 @@ +// 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. + +//! Defines windowing functions, like `shift`ing + +use crate::compute::concat; +use num::{abs, clamp}; +use std::sync::Arc; + +use crate::{ + array::{make_array, ArrayData, PrimitiveArray}, + datatypes::ArrowPrimitiveType, + error::Result, +}; +use crate::{ + array::{Array, ArrayRef}, + buffer::MutableBuffer, +}; + +/// Shifts array by defined number of items (to left or right) +pub fn shift<T>(values: &PrimitiveArray<T>, offset: i64) -> Result<ArrayRef> +where + T: ArrowPrimitiveType, +{ + // Compute slice + let slice_offset = clamp(offset, 0, values.len() as i64) as usize; + let length = values.len() - abs(offset) as usize; + let slice = values.slice(slice_offset, length); + + // Generate array with remaining `null` items + let nulls = abs(offset as i64) as usize; + + let mut null_array = MutableBuffer::new(nulls); + let mut null_data = MutableBuffer::new(nulls * T::get_byte_width()); + null_array.extend_zeros(nulls); + null_data.extend_zeros(nulls * T::get_byte_width()); + + let null_data = ArrayData::new( + T::DATA_TYPE, + nulls as usize, + Some(nulls), + Some(null_array.into()), + 0, + vec![null_data.into()], + vec![], + ); + + // Concatenate both arrays, add nulls after if shift > 0 else before + let null_arr = make_array(Arc::new(null_data)); + if offset > 0 { + concat(&[slice.as_ref(), null_arr.as_ref()]) + } else { + concat(&[null_arr.as_ref(), slice.as_ref()]) + } +} + +#[cfg(test)] +mod tests { + use crate::array::Int32Array; + + use super::*; + + #[test] + fn test_shift_neg() { + let a: Int32Array = vec![Some(1), None, Some(4)].into(); + let res = shift(&a, -1).unwrap(); + + let b = res.as_any().downcast_ref::<Int32Array>().unwrap(); + assert_eq!(a.len(), res.len()); + assert_eq!(false, b.is_valid(0)); + assert_eq!(1, b.value(1)); + assert_eq!(false, b.is_valid(2)); Review comment: FWIW I agree with @ritchie46 that I expect `shift([1,NULL,4], -1)` to shift LEFT -- so `[NULL, 4, NULL]` rather than right ( aka [NULL, 1, NULL]`) I don't think Postgres has any similar function I could find to guide us. I would vote to be consistent with Pandas -- which appears to shift right with a positive shift: https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.shift.html ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected]
