import matplotlib.pyplot as plt

for i in xrange(1, 4):
    for j in xrange(1, 5):
        plt.subplot(3, 4, (i-1)*4+j, xticks=[], yticks=[], frameon=False)
        plt.text(0.5, 0.5, '%i , %i' % (i, j))

plt.savefig("axes_numbers.png")
plt.show()