Function shift

arrow-select/src/window.rs:54–79

Shifts array by defined number of items (to left or right) A positive value for `offset` shifts the array to the right a negative value shifts the array to the left. # Examples ``` # use arrow_array::Int32Array; # use arrow_select::window::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

(array: &dyn Array, offset: i64)

/// assert_eq!(res.as_ref(), &expected);
/// ```
pub fn shift(array: &dyn Array, offset: i64) -> Result<ArrayRef, ArrowError> {
    let value_len = array.len() as i64;
    if offset == 0 {
        Ok(make_array(array.to_data()))
    } else if offset == i64::MIN || abs(offset) >= value_len {
        Ok(new_null_array(array.data_type(), array.len()))
    } else {
        // Concatenate both arrays, add nulls after if shift > 0 else before
        if offset > 0 {
            let length = array.len() - offset as usize;
            let slice = array.slice(0, length);

            // Generate array with remaining `null` items
            let null_arr = new_null_array(array.data_type(), offset as usize);
            concat(&[null_arr.as_ref(), slice.as_ref()])
        } else {
            let offset = -offset as usize;
            let length = array.len() - offset;
            let slice = array.slice(offset, length);

            // Generate array with remaining `null` items
            let null_arr = new_null_array(array.data_type(), offset);
            concat(&[slice.as_ref(), null_arr.as_ref()])
        }
    }
}

#[cfg(test)]
mod tests {