 An overall shape of such data is hard to visualise when data points are given by coordinates in a high-dimensional Euclidean space. More general data can be represented by an abstract graph with weights or distances on links between data points.
<clarity>  An overall shape of such data is hard to visualise when data points are given by coordinates in a high-dimensional Euclidean space. More general data can be represented by an abstract graph with weights or distances on links between data points.
 An overall shape of a noisy cloud of points sampled from a non-linear object that is more complicated than a union of disjoint clusters.