1. A computer implemented method of analysing a plurality of molecules, the method comprising: a) defining a plurality of features; b) determining which of the plurality of features is present in each of the molecules; c) computing a kernel function for each pair of the plurality of molecules, the kernel function being representative of the number of features present in both molecules of the pairs; and d) using the kernel function in a kernel based learning algorithm to model the relationship between the features and a property of the molecules.