Mallet主题模型-结果与序列化文件不一致

Question

我用Mallet训练了一个主题模型，我想序列化它以备将来使用。我在两个测试文档上运行了它，然后对它进行反序列化，并在相同的文档上运行加载的模型，结果完全不同。

我保存/加载文档的方式有什么问题吗（附代码）？

谢谢！

List<Pipe> pipeList = initPipeList();
// Begin by importing documents from text to feature sequences
InstanceList instances = new InstanceList(new SerialPipes(pipeList));
for (String document : documents) {
    Instance inst = new Instance(document, "","","");
    instances.addThruPipe(inst);
}
ParallelTopicModel model = new ParallelTopicModel(numTopics, alpha_t * numTopics, beta_w);
model.addInstances(instances);
model.setNumThreads(numThreads);
model.setNumIterations(numIterations);
model.estimate();
printProbabilities(model, "doc 1"); // I replaced the contents of the docs due to copywrite issues
printProbabilities(model, "doc 2");
model.write(new File("model.bin"));
model = ParallelTopicModel.read("model.bin");
printProbabilities(model, "doc 1");
printProbabilities(model, "doc 2");

printProbabilities():的定义

public void printProbabilities(ParallelTopicModel model, String doc) {
    List<Pipe> pipeList = initPipeList();
    InstanceList instances = new InstanceList(new SerialPipes(pipeList));
    instances.addThruPipe(new Instance(doc, "", "", ""));
    double[] probabilities = model.getInferencer().getSampledDistribution(instances.get(0), 10, 1, 5);
    for (int i = 0; i < probabilities.length; i++) {
        double probability = probabilities[i];
        if (probability > 0.01) {
            System.out.println("Topic " + i + ", probability: " + probability);
        }
    }
}

Answer 1

您必须使用相同的管道进行训练和分类。在转换过程中，管道的数据字母表会随着每个训练实例而更新。您不能使用新的SerialPipe（pipeList）生成相同的管道，因为它的数据字母表为空。保存/加载包含管道和模型的管道或实例列表，并使用该管道添加测试实例。

Answer 2

如果你不修复随机种子，每次运行Mallet都会给你一个不同的主题模型（主题的数量会排列，有些主题略有不同，其他主题则非常不同）。

修复随机种子以获得可复制的主题。