I didn't understand why i can not see 20 dots with the below command,

but i just see 3 dots at the graph.

import pylab as P

import numpy as N

a1 = N.ndarray(shape=(10,2))*2

x = a1[:,0]

y = a1[:,1]

a2 = N.ndarray(shape=(10,2))+10

xx = a2[:,0]

yy = a2[:,1]

n_x = N.append(x,xx)

n_y = N.append(y,yy)

P.scatter(n_x, n_y, alpha=0.5)

P.xlim(xmin=n_x.min()*10, xmax=n_x.max()*10)

P.ylim(ymin=n_y.min()*10, ymax=n_y.max()*10)

P.plot(n_x, n_y, 's', alpha=0.7, ms=3)

P.show()

Normally i have 20 different points to be plotted but because they are

so close values it just plots three of them. Any idea how i can fix

it?