nevi-me commented on a change in pull request #386:
URL: https://github.com/apache/arrow-rs/pull/386#discussion_r643581616
##########
File path: arrow/src/compute/kernels/window.rs
##########
@@ -33,56 +32,120 @@ use crate::{array::PrimitiveArray,
datatypes::ArrowPrimitiveType, error::Result}
/// use arrow::compute::shift;
///
/// let a: Int32Array = vec![Some(1), None, Some(4)].into();
+///
/// // shift array 1 element to the right
/// let res = shift(&a, 1).unwrap();
/// let expected: Int32Array = vec![None, Some(1), None].into();
-/// assert_eq!(res.as_ref(), &expected)
+/// assert_eq!(res.as_ref(), &expected);
+///
+/// // shift array 1 element to the left
+/// let res = shift(&a, -1).unwrap();
+/// let expected: Int32Array = vec![None, Some(4), None].into();
+/// assert_eq!(res.as_ref(), &expected);
+///
+/// // shift array 0 element, although not recommended
+/// let res = shift(&a, 0).unwrap();
+/// let expected: Int32Array = vec![Some(1), None, Some(4)].into();
+/// assert_eq!(res.as_ref(), &expected);
+///
+/// // shift array 3 element tot he right
+/// let res = shift(&a, 3).unwrap();
+/// 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,
{
- // 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 value_len = values.len() as i64;
+ if offset == 0 {
+ Ok(values.slice(0, values.len()))
Review comment:
Same comment as #388
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