Random walk (with animated graph)

Random walk of particles and calculation of their dispersion coefficient

The code is full of explanation notes, and is a solution to this question:
A. Consider an array of (n x n) particles initially equally positioned apart from each other by dx=1 and dy=1. Allow these particles to move walk randomly with time in a space much greater than the originally occupied space of (ndx x ndy). Calculate the average square distance between the particles and plot its ratio to the time step . This is the diffusion/dispersion coefficient.