An example to visualize how to vectorize the probability distribution. The walker takes 4 steps. In this example, the probability distribution of quantum walks on an infinite graph is shown in the figure and we vectorize the probability distribution as (0.17032, 0, 0.0834, 0, 0.25794, 0, 0.35851, 0, 0.12983). Also according to the approach raised above, we vectorize the probability distribution of quantum walks on a finite graph as (0, 0, 0.24286, 0.04181, 0.35087, 0.04297, 0.32149, 0, 0).