I'm trying to create a CDF but at the end of the graph, there is a vertical line, shown below:

I've read that his is because matplotlib uses the end of the bins to draw the vertical lines, which makes sense, so I added into my code as:

bins = sorted(X) + [np.inf]

where X is the data set I'm using and set the bin size to this when plotting:

plt.hist(X, bins = bins, cumulative = True, histtype = 'step', color = 'b')

This does remove the line at the end and produce the desired effect, however when I normalise this graph now it produces an error:

ymin = max(ymin*0.9, minimum) if not input_empty else minimum

UnboundLocalError: local variable 'ymin' referenced before assignment

Is there anyway to either normalise the data with

bins = sorted(X) + [np.inf]

in my code or is there another way to remove the line on the graph?

An alternative way to plot a CDF would be as follows (in my example, X is a bunch of samples drawn from the unit normal):

import numpy as np
import matplotlib.pyplot as plt

X = np.random.randn(10000)
n = np.arange(1,len(X)+1) / np.float(len(X))
Xs = np.sort(X)
fig, ax = plt.subplots()
ax.step(Xs,n)