cumulative distribution plots python

Question

I am doing a project using python where I have two arrays of data. Let's call them pc and pnc. I am required to plot a cumulative distribution of both of these on the same graph. For pc it is supposed to be a less than plot i.e. at (x,y), y points in pc must have value less than x. For pnc it is to be a more than plot i.e. at (x,y), y points in pnc must have value more than x.

I have tried using histogram function - pyplot.hist. Is there a better and easier way to do what i want? Also, it has to be plotted on a logarithmic scale on the x-axis.

Answer 1

You were close. You should not use plt.hist as numpy.histogram, that gives you both the values and the bins, than you can plot the cumulative with ease:

import numpy as np
import matplotlib.pyplot as plt

# some fake data
data = np.random.randn(1000)
# evaluate the histogram
values, base = np.histogram(data, bins=40)
#evaluate the cumulative
cumulative = np.cumsum(values)
# plot the cumulative function
plt.plot(base[:-1], cumulative, c='blue')
#plot the survival function
plt.plot(base[:-1], len(data)-cumulative, c='green')

plt.show()