Function rank

pub fn rank(
    array: &dyn Array,
    options: Option<SortOptions>,
) -> Result<Vec<u32>, ArrowError>

Assigns a rank to each value in array based on its position in the sorted order

Where values are equal, they will be assigned the highest of their ranks, leaving gaps in the overall rank assignment

let array = StringArray::from(vec![Some("foo"), None, Some("foo"), None, Some("bar")]);
let ranks = rank(&array, None).unwrap();
assert_eq!(ranks, &[5, 2, 5, 2, 3]);