shift_str

simd_kernels::kernels::window

Function shift_str 

Source 
pub fn shift_str<T: Integer>(
    arr: StringAVT<'_, T>,
    shift_offset: isize,
) -> Result<StringArray<T>, KernelError>
Expand description

Shifts string array elements with UTF-8 integrity and bidirectional offset support.

String shifting function supporting both LAG and LEAD operations through signed offset parameter. Maintains UTF-8 encoding integrity while providing flexible positional access for textual sequence analysis.

§Parameters

  • arr - String array view containing textual data for shifting
  • shift_offset - Signed offset: positive for LEAD (forward), negative for LAG (backward), zero for identity

§Returns

Returns Result<StringArray<T>, KernelError> containing:

  • Success: Shifted string values maintaining UTF-8 integrity
  • Error: KernelError if string processing encounters issues
  • Empty strings for positions beyond data boundaries
  • Null mask reflecting validity of shifted string positions

§Shift Semantics

  • Positive offset: LEAD operation accessing future string values
  • Negative offset: LAG operation accessing historical string values
  • Zero offset: Identity operation (returns cloned array slice)
  • Boundary conditions: Out-of-range positions produce empty strings

§Examples

ⓘ
use minarrow::StringArray;
use simd_kernels::kernels::window::shift_str;

let arr = StringArray::<u32>::from_slice(&["one", "two", "three"]);
let back = shift_str((&arr, 0, arr.len()), -1).unwrap(); // LAG
let forward = shift_str((&arr, 0, arr.len()), 1).unwrap(); // LEAD
// back:    ["", "one", "two"]
// forward: ["two", "three", ""]