java 随机森林算法代码

下面是一个简单的Java随机森林算法的实现代码示例：

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class RandomForest {

    private List<DecisionTree> forest;
    private int numTrees;
    private int maxDepth;
    private int minLeafSize;
    private int numFeatures;

    public RandomForest(int numTrees, int maxDepth, int minLeafSize, int numFeatures) {
        this.numTrees = numTrees;
        this.maxDepth = maxDepth;
        this.minLeafSize = minLeafSize;
        this.numFeatures = numFeatures;
        this.forest = new ArrayList<DecisionTree>();
    }

    public void train(List<DataPoint> data) {
        int numDataPoints = data.size();
        for (int i = 0; i < numTrees; i++) {
            // Randomly select a subset of features
            List<Integer> featureIndices = new ArrayList<Integer>();
            for (int j = 0; j < numFeatures; j++) {
                featureIndices.add(j);
            }
            Collections.shuffle(featureIndices);
            featureIndices = featureIndices.subList(0, numFeatures);

            // Randomly select a subset of data points
            List<DataPoint> subset = new ArrayList<DataPoint>();
            for (int j = 0; j < numDataPoints; j++) {
                int index = new Random().nextInt(numDataPoints);
                subset.add(data.get(index));
            }

            // Build a decision tree using the selected features and data points
            DecisionTree tree = new DecisionTree(maxDepth, minLeafSize, featureIndices);
            tree.train(subset);
            forest.add(tree);
        }
    }

    public int predict(DataPoint data) {
        int numTrees = forest.size();
        int[] predictions = new int[numTrees];
        for (int i = 0; i < numTrees; i++) {
            predictions[i] = forest.get(i).predict(data);
        }

        // Return the mode of the predictions
        int mode = predictions[0];
        int maxCount = 0;
        for (int i = 0; i < numTrees; i++) {
            int count = 0;
            for (int j = 0; j < numTrees; j++) {
                if (predictions[j] == predictions[i]) {
                    count++;
                }
            }
            if (count > maxCount) {
                mode = predictions[i];
                maxCount = count;
            }
        }
        return mode;
    }
}

请注意，上述代码中的 `DataPoint` 和 `DecisionTree` 类并未给出，因此你需要根据自己的数据结构实现它们。此外，这个实现仅作为参考，你可以根据自己的需求进行修改和改进。