Function indxvec::merge::merge_indexed

pub fn merge_indexed<T>(
    v1: &[T], 
    idx1: &[usize], 
    v2: &[T], 
    idx2: &[usize]
) -> (Vec<T>, Vec<usize>) where
    T: PartialOrd + Copy, 

Merges two ascending sort indices. Data is not shuffled at all, v2 is just concatenated onto v1 in one go and both remain in their original order. Returns the concatenated vector and a new valid sort index into it.