Complex sentence: The non-linear methods can be broadly classified into two groups: those which actually provide a mapping (either from the high dimensional space to the low dimensional embedding or vice versa), and those that just give a visualisation.
Split into simpler sentences: The non-linear methods can be broadly classified into two groups. Those which actually provide a mapping (either from the high dimensional space to the low dimensional embedding or vice versa) and those that just give a visualisation.