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65 changes: 53 additions & 12 deletions arrow/src/compute/kernels/window.rs
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@
//! Defines windowing functions, like `shift`ing

use crate::array::{Array, ArrayRef};
use crate::{array::PrimitiveArray, datatypes::ArrowPrimitiveType, error::Result};
use crate::error::Result;
use crate::{
array::{make_array, new_null_array},
compute::concat,
Expand Down Expand Up @@ -56,23 +56,20 @@ use num::{abs, clamp};
/// let expected: Int32Array = vec![None, None, None].into();
/// assert_eq!(res.as_ref(), &expected);
/// ```
pub fn shift<T>(values: &PrimitiveArray<T>, offset: i64) -> Result<ArrayRef>
where
T: ArrowPrimitiveType,
{
let value_len = values.len() as i64;
pub fn shift(array: &Array, offset: i64) -> Result<ArrayRef> {
let value_len = array.len() as i64;
if offset == 0 {
Ok(make_array(values.data_ref().clone()))
Ok(make_array(array.data_ref().clone()))
} else if offset == i64::MIN || abs(offset) >= value_len {
Ok(new_null_array(&T::DATA_TYPE, values.len()))
Ok(new_null_array(array.data_type(), array.len()))
} else {
let slice_offset = clamp(-offset, 0, value_len) as usize;
let length = values.len() - abs(offset) as usize;
let slice = values.slice(slice_offset, length);
let length = array.len() - abs(offset) as usize;
let slice = array.slice(slice_offset, length);

// Generate array with remaining `null` items
let nulls = abs(offset) as usize;
let null_arr = new_null_array(&T::DATA_TYPE, nulls);
let null_arr = new_null_array(array.data_type(), nulls);

// Concatenate both arrays, add nulls after if shift > 0 else before
if offset > 0 {
Expand All @@ -86,7 +83,7 @@ where
#[cfg(test)]
mod tests {
use super::*;
use crate::array::Int32Array;
use crate::array::{Float64Array, Int32Array, Int32DictionaryArray};

#[test]
fn test_shift_neg() {
Expand All @@ -104,6 +101,50 @@ mod tests {
assert_eq!(res.as_ref(), &expected);
}

#[test]
fn test_shift_neg_float64() {
let a: Float64Array = vec![Some(1.), None, Some(4.)].into();
let res = shift(&a, -1).unwrap();
let expected: Float64Array = vec![None, Some(4.), None].into();
assert_eq!(res.as_ref(), &expected);
}

#[test]
fn test_shift_pos_float64() {
let a: Float64Array = vec![Some(1.), None, Some(4.)].into();
let res = shift(&a, 1).unwrap();
let expected: Float64Array = vec![None, Some(1.), None].into();
assert_eq!(res.as_ref(), &expected);
}

#[test]
fn test_shift_neg_int32_dict() {
let a: Int32DictionaryArray = [Some("alpha"), None, Some("beta"), Some("alpha")]
.iter()
.copied()
.collect();
let res = shift(&a, -1).unwrap();
let expected: Int32DictionaryArray = [None, Some("beta"), Some("alpha"), None]
.iter()
.copied()
.collect();
assert_eq!(res.as_ref(), &expected);
}

#[test]
fn test_shift_pos_int32_dict() {
let a: Int32DictionaryArray = [Some("alpha"), None, Some("beta"), Some("alpha")]
.iter()
.copied()
.collect();
let res = shift(&a, 1).unwrap();
let expected: Int32DictionaryArray = [None, Some("alpha"), None, Some("beta")]
.iter()
.copied()
.collect();
assert_eq!(res.as_ref(), &expected);
}

#[test]
fn test_shift_nil() {
let a: Int32Array = vec![Some(1), None, Some(4)].into();
Expand Down