def make_illustration_snapshot():
fig = plt.figure()
ax = fig.gca()
model = vicsek_model_factory(model='angular',
n=200, L=100.0, eta=0.2, v_0=0.5)
for _ in range(100):
model.iterate()
ejm_rcparams.set_pretty_plots(use_latex=True, use_pgf=True)
ejm_rcparams.prettify_axes(ax)
ax.set_xlim(-model.L_half, model.L_half)
ax.set_ylim(-model.L_half, model.L_half)
ax.set_aspect('equal')
i_source = np.argmin(np.sum(np.square(model.r), axis=1))
r_i = model.r[i_source]
c = plt.Circle(r_i, radius=model.r_v, fill=False, edgecolor='red')
ax.add_patch(c)
colors = np.zeros([model.n])
colors[i_source] = 1.0
i_neighbs = model._neighbs(i_source)
for i_neighb in i_neighbs:
colors[i_neighb] = 0.5
s = 2.0
ax.quiver(model.r[:, 0], model.r[:, 1],
s * model.L * model.u[:, 0], s * model.L * model.u[:, 1],
colors, pivot='mid', edgecolor='none')
ax.axis('off')
plt.savefig('vicsek_snapshot_demo.pdf', bbox_inches='tight',
transparent=True)
def eta_scan(model, n, L, v_0, num_equil, num_measure, etas):
for eta in etas:
m = vicsek_model_factory(model=model, n=n, L=L, eta=eta, v_0=v_0)
# Equilibrate
for _ in range(num_equil):
m.iterate()
# Take measurements
mags = []
for _ in range(num_measure):
m.iterate()
mags.append(m.macro_u_mag)
yield eta, np.mean(mags), np.std(mags), len(mags)
def make_disordered_snapshot():
model = vicsek_model_factory(model='angular',
n=100, L=100.0, eta=0.8, v_0=0.5)
for _ in range(100):
model.iterate()
fig = plt.figure()
ax = fig.gca()
ejm_rcparams.set_pretty_plots(use_latex=True, use_pgf=True)
ejm_rcparams.prettify_axes(ax)
ax.set_xlim(-model.L_half, model.L_half)
ax.set_ylim(-model.L_half, model.L_half)
ax.set_aspect('equal')
s = 2.0
ax.quiver(model.r[:, 0], model.r[:, 1],
s * model.L * model.u[:, 0], s * model.L * model.u[:, 1],
pivot='mid', edgecolor='none')
ax.axis('off')
plt.savefig('vicsek_snapshot_disordered.pdf', bbox_inches='tight',
transparent=True)
m = vicsek_model_factory(model=model, n=n, L=L, eta=eta, v_0=v_0)
# Equilibrate
for _ in range(num_equil):
m.iterate()
# Take measurements
mags = []
for _ in range(num_measure):
m.iterate()
mags.append(m.macro_u_mag)
yield eta, np.mean(mags), np.std(mags), len(mags)
def make_vicsek_stats():
n = 2048
L = 32.0
v_0 = 0.5
num_equil = 100
num_measure = 500
for model in ('angular', 'vectorial'):
if model == 'angular':
etas = np.linspace(0.6, 0.8, 20)
else:
etas = np.linspace(0.55, 0.65, 20)
stats = eta_scan(model, n, L, v_0, num_equil, num_measure, etas)
np.savetxt('{}_stats.txt'.format(model), list(stats))
if __name__ == '__main__':
plot_vicsek(vicsek_model_factory(model='angular',
n=200, L=50.0, eta=0.05, v_0=0.5), 100)
