How to find the Entropy – Decision Tree Learning – Machine Learning
In this tutorial we will understand, how to find the entropy given the four probabilities p1=0.1, p2=0.2, p3=0.3 and p4=0.4 in the decision tree.
We know that the equation to find Entropy is,
Entropy = -∑pi * log2(pi)
We were give four probabilities, hence after expanding the equation will become,
Entropy =-p1∗log2(p1 )-p2∗log2(p2)-p3∗log2(p3 )-p4∗log2(p4 )
Now we will put the values of p1, p2, p3, and p4 in eqaution.
Entropy =-0.1∗log2(0.1 )-0.2∗log2(0.2)-0.3∗log2(0.3 )-0.4∗log2(0.4 )
The Entropy is 1.8462 for the given four Probabilities p1=0.1, p2=0.2, p3=0.3 and p4=0.4.
In this tutorial we understood, how to find the entropy given the probabilities in decision tree learning.