matplotlib: how to remove vertical line from cdf graph for datetime values

Question

The following code draws the cdf for datetime values:

import matplotlib.pyplot as plt
import matplotlib.dates as dates
import numpy as np; np.random.seed(42)
import pandas as pd

objDate = dates.num2date(np.random.normal(735700, 300, 700))

ser = pd.Series(objDate)
ax = ser.hist(cumulative=True, density=1, bins=500, histtype='step')

plt.show()

How can I remove the vertical line at the right-most end of graph? The approach mentioned here doesn't work as replacing line#9 with:

ax = ser.hist(cumulative=True, density=1, bins=sorted(objDate)+[np.inf], histtype='step')

gives

TypeError: can't compare datetime.datetime to float

Answer 1

The CDF is actually drawn as a polygon, which in matplotlib is defined by a path. A path is in turn defined by vertices (where to go) and codes (how to get there). The docs say that we should not directly alter these attributes, but we can make a new polygon derived from the old one that suits our needs.

poly = ax.findobj(plt.Polygon)[0]
vertices = poly.get_path().vertices

# Keep everything above y == 0. You can define this mask however
# you need, if you want to be more careful in your selection.
keep = vertices[:, 1] > 0

# Construct new polygon from these "good" vertices
new_poly = plt.Polygon(vertices[keep], closed=False, fill=False,
                       edgecolor=poly.get_edgecolor(),
                       linewidth=poly.get_linewidth())
poly.set_visible(False)
ax.add_artist(new_poly)
plt.draw()

You should arrive at something like the figure below: