There is an error in the formula in the entropy written on this slide. There should be a negative (-) sign preceding the sum:
Entropy = - \sum_i (p_i) \log_2 (p_i)−∑i?(pi?)log2?(pi?)
IG = 1
gini is another measurement of purity
In this project, we will again try to identify the authors in a body of emails, this time using a decision tree. The starter code is in decision_tree/dt_author_id.py.
Get the data for this mini project from here.
Once again, you‘ll do the mini-project on your own computer and enter your answers in the web browser. You can find the instructions for the decision tree mini-project here.
[ML] {ud120} Lesson 4: Decision Trees
原文：https://www.cnblogs.com/ecoflex/p/10987754.html