Experiment: from the above learning

Experiment: from the above learning, we can know that the core of ID3 should be to select the characteristics of the corresponding information gain criteria on each node of the decision tree and construct the tree recursively. The specific method is: from the root node (root Node) first, calculate the information gain of all possible features for the node, select the feature with the largest information gain as the feature of the node, and establish the sub node according to the different values of the feature; then call the above methods recursively for the sub node to build the decision tree; until the information gain of all features is small or there is no feature to choose, finally get a decision tree.The training set is as follows: