In [20]:

    

%matplotlib inline
%config InlineBackend.figure_format='retina'


    

In [31]:

    

import matplotlib.pyplot as plt
import numpy as np

p0s = np.arange(0, 1, 0.01)

def entropy (*ps):
	return - sum(ps * np.log2(ps))

etas = map(lambda p0: entropy(p0, 1-p0), p0s)


    

    




/home/ge/anaconda3/envs/lizards/lib/python2.7/site-packages/ipykernel/__main__.py:7: RuntimeWarning: divide by zero encountered in log2
/home/ge/anaconda3/envs/lizards/lib/python2.7/site-packages/ipykernel/__main__.py:7: RuntimeWarning: invalid value encountered in multiply

In [37]:

    

plt.plot(p0s, etas)
plt.ylim(-0.5, 1.5)
plt.title("Entropy Vs. P_0 in a two-part system");


    

In [35]:

    

entropy(0.5, 0.5)


    

    
Out[35]:





1.0

In [ ]:

    

# Information Gain

0.5 * entropy(0.5, 0.5) + 0.5 * entropy(1)


    

In [ ]: