Dear all,

I would like to plot a figure with double x-axes.

Unfortunately, it seems the ticks of the second x axis do not fit with what I want.

Here the example:

import numpy as np

import matplotlib.pyplot as plt

MM = np.array([ 1., 2., 4., 8., 16., 32.])

SS = np.array([64., 32., 16., 8., 4., 2.])

RR = np.array([2813, 1544, 895, 562, 459,409])

ax = plt.subplot(111)

ax.grid(True,which="both",ls="-",color='0.6')

ax.plot(MM, RR ,'-r')

ax2 = ax.twiny()

ax2.invert_xaxis()

ax2.plot(MM, RR, 'none')

ax2.set_xticks([64,32,16,8,4,2])

ax2.set_xticklabels(['64','32','16','8','4','2'])

plt.show()

As it can be noticed, the value 32 in the ax2 does not correspond to the second value but is put in the middle point of ax2. I would like to have it in the same vertical line of the second value of MM. This of course not only for 32 but for the value in SS. Basically I would like to have the main axis according to MM and a second ax with SS value in the same line of MM values.

I hope I made myself clear.

really really thanks and,

best regards