Editing Nonlinear dimensionality reduction (section)

=== RankVisu ===

RankVisu<ref>Lespinats S., Fertil B., Villemain P. and Herault J., [https://www.sciencedirect.com/science/article/pii/S0925231209001544 Rankvisu: Mapping from the neighbourhood network], Neurocomputing, vol. 72 (13–15), pp. 2964–2978, 2009.</ref> is designed to preserve rank of neighborhood rather than distance. RankVisu is especially useful on difficult tasks (when the preservation of distance cannot be achieved satisfyingly). Indeed, the rank of neighborhood is less informative than distance (ranks can be deduced from distances but distances cannot be deduced from ranks) and its preservation is thus easier.