Fig. 4

Clustering of mutations as an HMP. HMP consisting of two states (a), with a corresponding rainfall pattern that such a process would give rise to (b) and a corresponding histogram of inter-event distances (c). In this example of a hidden Markov process, there is a high probability (P=0.8) of being in or moving to the state with low intra-hotspot distance (λ=0.01), which generates closely spaced events. A more seldomly occurring state (P=0.2) with large inter-hotspot distance (λ=0.0001) generates events with large distance to their preceding neighbors. The process defined by these two states generates several distantly spaced hotspots of events, giving rise to two quite distinct horizontal bands in the RP. The same pattern can also be seen as two distinct peaks in the histogram of inter-event distances