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liblinear ライブラリ (Java) を操作しようとしています。ここにあるテンプレートを使用した非常に単純な例を使用しています。ケースの例は、形状が正方形か長方形かを判断することです。

ここに私のコードがあります:

import java.io.File;
import java.io.IOException;

import de.bwaldvogel.liblinear.Feature;
import de.bwaldvogel.liblinear.FeatureNode;
import de.bwaldvogel.liblinear.Linear;
import de.bwaldvogel.liblinear.Model;
import de.bwaldvogel.liblinear.Parameter;
import de.bwaldvogel.liblinear.Problem;
import de.bwaldvogel.liblinear.SolverType;

public class Main {

    static int NUM_OF_TS_EXAMPLES = 8;

    // 1 = square, -1 = non-square
    static double[] GROUPS_ARRAY = {1, 1, 1, 1, -1, -1, -1, -1};

    // squares
    static FeatureNode[] shape1 = {new FeatureNode(1, 2), new FeatureNode(2, 2)};
    static FeatureNode[] shape2 = {new FeatureNode(1, 4), new FeatureNode(2, 4)};
    static FeatureNode[] shape3 = {new FeatureNode(1, 9), new FeatureNode(2, 9)};
    static FeatureNode[] shape4 = {new FeatureNode(1, 10), new FeatureNode(2, 10)};

    // not squares
    static FeatureNode[] shape5 = {new FeatureNode(1, 5), new FeatureNode(2, 6)};
    static FeatureNode[] shape6 = {new FeatureNode(1, 3), new FeatureNode(2, 4)};
    static FeatureNode[] shape7 = {new FeatureNode(1, 6), new FeatureNode(2, 9)};
    static FeatureNode[] shape8 = {new FeatureNode(1, 4), new FeatureNode(2, 2)};

    // unknown squares
    static FeatureNode[] unkown1 = {new FeatureNode(1, 32), new FeatureNode(2, 32)};
    static FeatureNode[] unkown2 = {new FeatureNode(1, 4), new FeatureNode(2, 2)};
    static FeatureNode[] unkown3 = {new FeatureNode(1, 4), new FeatureNode(2, 2)};
    static FeatureNode[][] trainingSetWithUnknown = {
        shape1,
        shape2,
        shape3,
        shape4,
        shape5,
        shape6,
        shape7,
        shape8
    };
    public static void main(String[] args) throws IOException {

        Problem problem = new Problem();

        // number of training examples
        problem.l = NUM_OF_TS_EXAMPLES;

        // number of features
        problem.n = NUM_OF_TS_EXAMPLES + 1;

        // problem.x = ... // feature nodes
        problem.x = trainingSetWithUnknown;

        // problem.y = ... // target values
        problem.y = GROUPS_ARRAY;

        SolverType solver = SolverType.L2R_LR; // -s 0
        double C = 1.0; // cost of constraints violation
        double eps = 0.01; // stopping criteria

        Parameter parameter = new Parameter(solver, C, eps);
        Model model = Linear.train(problem, parameter);
        File modelFile = new File("model");
        model.save(modelFile);
        // load model or use it directly
        model = Model.load(modelFile);

        Feature[] instance = new FeatureNode[5];
        double prediction = Linear.predict(model, instance);
    }
}

実行した後、コンソールに次の結果が表示されます。

iter  1 act 1.969e-02 pre 1.966e-02 delta 4.283e-03 f 5.545e+00 |g| 9.192e+00 CG   1

Exception in thread "main" java.lang.NullPointerException
at de.bwaldvogel.liblinear.Linear.predictValues(Linear.java:370)
at de.bwaldvogel.liblinear.Linear.predict(Linear.java:316)
at Main.main(Main.java:73)

私は何を間違っていますか？

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2 に答える 2

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NullPointerExceptionその理由は、初期化されていない機能の配列を予測関数に渡しているためだと思います-instance最初に初期化してみてください：

Feature[] instance = { new FeatureNode(1, 4), new FeatureNode(2, 2) };
于 2012-11-29T21:25:05.013 に答える