from tree import tree as tree

from initialization import make_galaxy

import matplotlib.pyplot as plt

import numpy as np

import matplotlib.animation as animation

G = 0.0044995611

dt = 1 # Myrs

universe_size = 50

theta = 1.

N = 50

chi = 10. #softening

bodies = make_galaxy(N,chi,G)

sys = tree(bodies, G, universe_size, dt, theta, chi)

fig, (ax) = plt.subplots(1,1)

ax.set_xlim(-universe_size/2., universe_size/2.)

ax.set_ylim(-universe_size/2., universe_size/2.)

ax.set_title('N =' + str(N))

points = ax.plot( *([[], []]*N), marker="o", color='black', markersize=1) #change the size

def init():

for j in range(N):

points[j].set_data([], [])

return(points)

def update(n):

points[j].set_data(x[j],y[j])

ani = animation.FuncAnimation(fig, update, init_func=init, frames=10000, interval=1)

plt.show()