使用arff文件存储数据

Question

我正在使用此示例为myka projext创建我的.arff文件,请在此处输入链接说明.

double[][] data = {{4058.0, 4059.0, 4060.0, 214.0, 1710.0, 2452.0, 2473.0, 2474.0, 2475.0, 2476.0, 2477.0, 2478.0, 2688.0, 2905.0, 2906.0, 2907.0, 2908.0, 2909.0, 2950.0, 2969.0, 2970.0, 3202.0, 3342.0, 3900.0, 4007.0, 4052.0, 4058.0, 4059.0, 4060.0}, 
                       {19.0, 20.0, 21.0, 31.0, 103.0, 136.0, 141.0, 142.0, 143.0, 144.0, 145.0, 146.0, 212.0, 243.0, 244.0, 245.0, 246.0, 247.0, 261.0, 270.0, 271.0, 294.0, 302.0, 340.0, 343.0, 354.0, 356.0, 357.0, 358.0}};

    int numInstances = data[0].length;

    FastVector atts = new FastVector();
    ArrayList<Instance> instances = new ArrayList<Instance>();
    for (int dim = 0; dim < 2; dim++) {
        // Create new attribute / dimension
        Attribute current = new Attribute("Attribute" + dim, dim);
        // Create an instance for each data object


        if (dim == 0) {
            for (int obj = 0; obj < numInstances; obj++) {
                instances.add(new SparseInstance(0));

            }
        }

        // Fill the value of dimension "dim" into each object
        for (int obj = 0; obj < numInstances; obj++) {
            instances.get(obj).setValue(current, data[dim][obj]);
            System.out.println(instances.get(obj));
        }

        // Add attribute to total attributes
        atts.addElement(current);

    }

     // Create new dataset
    Instances newDataset = new Instances("Dataset", atts, instances.size());

    // Fill in data objects
    for (Instance inst : instances) {
        newDataset.add(inst);       
    }

    BufferedWriter writer = new BufferedWriter(new FileWriter("test.arff"));
    writer.write(newDataset.toString());
    writer.flush();
    writer.close();
}

我注意到结果格式将行元素的向量放在.arff文件的列中.我想将整行放在.arff文件的第一行.我怎么能这样做？对于我的情况,2d向量的最后一列表示行数据的标签.

我的arff文件的预期结果:

4058.0, 4059.0, 4060.0, 214.0, 1710.0, 2452.0, 2473.0, 2474.0, 2475.0, 2476.0, 2477.0, 2478.0, 2688.0, 2905.0, 2906.0, 2907.0, 2908.0, 2909.0, 2950.0, 2969.0, 2970.0, 3202.0, 3342.0, 3900.0, 4007.0, 4052.0, 4058.0, 4059.0, 4060.0, 1 // for example the first row
 19.0, 20.0, 21.0, 31.0, 103.0, 136.0, 141.0, 142.0, 143.0, 144.0, 145.0, 146.0, 212.0,  
 243.0, 244.0, 245.0, 246.0, 247.0, 261.0, 270.0, 271.0, 294.0, 302.0, 340.0, 343.0, 
 354.0, 356.0, 357.0, 358.0, 0 // the second row.

Answer 1

示例中的代码将表中的每个列视为一个实例(因此有29个实例,每个实例具有两个属性).听起来你想将每一行视为一个实例(给出两个实例,每个实例有29个属性):

double[][] data = {
                    {4058.0, 4059.0, ... }, /* first instance */
                    {19.0, 20.0, ... }      /* second instance */
                  };

int numAtts = data[0].length;
FastVector atts = new FastVector(numAtts);
for (int att = 0; att < numAtts; att++)
{
    atts.addElement(new Attribute("Attribute" + att, att));
}

int numInstances = data.length;
Instances dataset = new Instances("Dataset", atts, numInstances);
for (int inst = 0; inst < numInstances; inst++)
{
    dataset.add(new Instance(1.0, data[inst]));
}

BufferedWriter writer = new BufferedWriter(new FileWriter("test.arff"));
writer.write(dataset.toString());
writer.flush();
writer.close();

我替换SparseInstance为Instance,因为几乎所有的属性值都是非零的.请注意,在Weka 3.7中Instance已成为一个接口,DenseInstance应该使用它.此外,FastVector已被弃用赞成Java的ArrayList.