import pylab

x=[0.1,0.2,0.3,0.4]
y=[0.2,0.4,0.6,0.8]


pylab.figure(num=1,frameon=False)
circle = pylab.Circle((0, 0), 1.025, color="black", fill=None)
ax = pylab.subplot(111, aspect=1)
ax.add_artist(circle)
ax.scatter(x,y,s=30, c='red', marker='o', edgecolor='red')
pylab.xlim([-1.1,1.1])
pylab.ylim([-1.1,1.1])
ax.xaxis.set_visible(False)
ax.yaxis.set_visible(False)
pylab.title("Plot")
pylab.show()