Matplotlib: xticks labels not showing - python-2.7

Question

I'm new to matplotlib and I'm having a small problem. I'm trying to make 3 plots stacked on top of each other, sharing the x axis and with 2 different y axis.
This is my current code
import numpy as np
import matplotlib.pyplot as plt
periods = range(1,13)
n0 = [4.2, 6.7, 10.6, 51.3, 339, 45.6, 56.3, 112.9, 182.7, 185.7, 126.2, 25.39]
alp = [2.12, 2.14, 2.19, 2.35, 2.54, 2.33, 2.34, 2.43, 2.45, 2.46, 2.466, 2.249]
B = [0.045, 0.041, 0.04, 0.04, 0.057, 0.048, 0.044, 0.057, 0.054, 0.065, 0.06, 0.045]
emin = [166, 201.9, 215, 270.7, 351.8, 263.7, 302.2, 323.6, 328.7, 346.1, 279.5, 259.8]
emax = [21806, 28407, 5706, 22087, 17978, 11699, 19440, 17988, 26938, 14812, 14195, 26121]
eq = [7.8, 11.8, 13.3, 15.2, 8.87, 10.5, 13.8, 7.6, 11.5, 7.4, 6.4, 13.5]
f, (ax1, ax2, ax3) = plt.subplots(3, sharex = True)
ax1.scatter(periods, emin, c="k")
ax1.set_ylabel(r"$E_{min}")
ax1.yaxis.set_ticks(range(160, 380, 40))
ax4 = ax1.twinx()
ax4.scatter(periods, n0, c="r")
ax4.set_ylabel(r"$N_0$", color = 'r')
ax4.tick_params(colors = 'r')
ax4.yaxis.set_ticks(np.arange(20, 340, 50))
ax2.scatter(periods, emax, c="k")
ax2.set_ylabel(r"$E_{max}$")
ax2.yaxis.set_ticks(np.arange(5000, 30000, 5000))
ax5 = ax2.twinx()
ax5.scatter(periods, alpha, c="r")
ax5.set_ylabel("alp", color = 'r')
ax5.tick_params(colors = 'r')
ax5.yaxis.set_ticks(np.arange(2.1, 2.6, 0.1))
ax3.scatter(periods, eq, c="k")
ax3.set_ylabel("Eq")
ax3.yaxis.set_ticks(np.arange(6, 15, 2))
ax3.set_xlabel("Periods")
ax6 = ax3.twinx()
ax6.scatter(periods, B, c="r")
ax6.set_ylabel("B", color = 'r')
ax6.tick_params(colors = 'r')
ax6.yaxis.set_ticks(np.arange(0.02, 0.09, 0.02))
ax6.xaxis.set_ticks(range(1,13))
f.subplots_adjust(hspace = 0)
plt.setp([a.get_xticklabels() for a in f.axes[:-1]], visible=False)
plt.show()
But the x axis labels are not being shown. The label itself ("Periods") is fine, but the ticks aren't. I've tried to change the line
ax6.xaxis.set_ticks(range(1,13))
to every other number, but still doesn't work. Any help?
On a side note, how to rotate the y axis labels by 90 degrees so that they are horizontal? I've tried including rotation = 90 in the ylabel but it doesn't change (though other values work).
Thanks a lot
Edit: Forgot to add, if I erase the twinx axes it works fine

Answer 1

In order for your x ticks to appear you need to change the second to last line and set visible = True. In order to rotate the y labels by 90 degrees, use rotation = as you are doing, but set the rotation to 0. Doing this may make your labels and your ticks overlap. You can remove this by using the labelpad = in your ax.set_ylabel(). This is the spacing between the axis and the label.
f, (ax1, ax2, ax3) = plt.subplots(3, sharex = True)
ax1.scatter(periods, emin, c="k")
ax1.set_ylabel(r"$E_{min}$",rotation=0,labelpad=20)
ax1.yaxis.set_ticks(range(160, 380, 40))
ax4 = ax1.twinx()
ax4.scatter(periods, n0, c="r")
ax4.set_ylabel(r"$N_0$", color = 'r',rotation=0,labelpad=10)
ax4.tick_params(colors = 'r')
ax4.yaxis.set_ticks(np.arange(20, 340, 50))
ax2.scatter(periods, emax, c="k")
ax2.set_ylabel(r"$E_{max}$",rotation=0,labelpad=20)
ax2.yaxis.set_ticks(np.arange(5000, 30000, 5000))
ax5 = ax2.twinx()
ax5.scatter(periods, alp, c="r")
ax5.set_ylabel("alp", color = 'r',rotation=0,labelpad=15)
ax5.tick_params(colors = 'r')
ax5.yaxis.set_ticks(np.arange(2.1, 2.6, 0.1))
ax3.scatter(periods, eq, c="k")
ax3.set_ylabel("Eq",rotation=0,labelpad=20)
ax3.yaxis.set_ticks(np.arange(6, 15, 2))
ax3.set_xlabel("Periods")
ax6 = ax3.twinx()
ax6.scatter(periods, B, c="r")
ax6.set_ylabel("B", color = 'r',rotation=0,labelpad=10)
ax6.tick_params(colors = 'r')
ax6.yaxis.set_ticks(np.arange(0.02, 0.09, 0.02))
ax1.xaxis.set_ticks(np.arange(1, 13, 1))
f.subplots_adjust(hspace = 0,left=0.14,right=0.90)
plt.setp([a.get_xticklabels() for a in f.axes[:-1]], visible=True)
plt.show()
This produces the following plot:
You may want to experiment with the labelpad to get the labels exactly where you want them as the length of your tick labels are not the same for each axis.