if not os.path.exists(img_folder):

os.makedirs(img_folder);

fig_num=len(xy);

mydpi=100;

for i in range(fig_num):

#fig = plt.figure(figsize=(32/mydpi,32/mydpi))

fig = plt.figure(figsize=(128/mydpi,128/mydpi))

plt.xlim(-200, 200)

plt.ylim(-200, 200)

plt.axis('off');

color=['r','b','g','k','y','m','c'];

for j in range(len(xy[0])):

#plt.scatter(xy[i,j,1],xy[i,j,0],c=color[j%len(color)],s=0.5);

plt.scatter(xy[i,j,1],xy[i,j,0],c=color[j%len(color)],s=5);

fig.savefig(img_folder+prefix+"_"+str(i)+".png",dpi=mydpi);