xtickNames = plt.setp(ax, xticklabels=[str(v) for v in values])
sets the xticklabels
property.
plt.setp(xtickNames)
prints the configurable properties of xtickNames
to the screen.
So just use the first command to set the xticklabels
without printing to the screen. Alternatively, you could use
ax.set_xticklabels(map(str, values))