x-axis inverted unexpectedly by pandas.plot(…)

Question

X axis was inverted automatically and unexpectedly when plotting a series of data against another series of data using pandas. Please look at my code below. How can I ensure

Answer 1

You can enforce a direction for each plot:

(t,b)= ax.get_xlim()  ## Added for clarity
if t > b:
    ax.set_xlim((b,t))

or

if ax.xaxis_inverted():
    ax.invert_xaxis()

(the latter just do the explicit three-line version, though.)