To display a similarity matrix of n objects, we need n
2
cells or n
2
2
cells in the case of half matrix. In practice, usually
it is not necessary to display all cells in a matrix. To this
end, we should be able to have some parameters to control
whether a cell is displayed or not. Depending on what parameter
setting will be used, we have two variants of nearest
neighbor visualization: k-nearest neighbor setting and distance
threshold setting