在weka中添加新实例

让我们从一些亮点开始。

• weka将每个实例值存储为double []。因此，您创建double [] instancevalue1并将值添加到此数组。
• 偶数字符串也存储在此double []中。您可以使用以下代码添加字符串值：

instancevalue1 [0] = dataRaw.attribute（0）.addStringValue（“这是一个字符串！”）;

• 实例是接口，由两个类{SparseInstance，DenseInstance}实现。我们使用以下代码将值数组添加到数据集中：

dataRaw.add（new DenseInstance（1.0，instancevalue1））;

这是完整的运行示例：

import java.util.ArrayList;import weka.core.Attribute;import weka.core.DenseInstance;import weka.core.Instance;import weka.core.Instances;public class Program {    public static void main(String[] args) {        ArrayList<Attribute> atts = new ArrayList<Attribute>(2);        ArrayList<String> classVal = new ArrayList<String>();        classVal.add("A");        classVal.add("B");        atts.add(new Attribute("content",(ArrayList<String>)null));        atts.add(new Attribute("@@class@@",classVal));        Instances dataRaw = new Instances("TestInstances",atts,0);        System.out.println("Before adding any instance");        System.out.println("--------------------------");        System.out.println(dataRaw);        System.out.println("--------------------------");        double[] instancevalue1 = new double[dataRaw.numAttributes()];        instancevalue1[0] = dataRaw.attribute(0).addStringValue("This is a string!");        instancevalue1[1] = 0;        dataRaw.add(new DenseInstance(1.0, instancevalue1));        System.out.println("After adding a instance");        System.out.println("--------------------------");        System.out.println(dataRaw);        System.out.println("--------------------------");        double[] instancevalue2 = new double[dataRaw.numAttributes()];        instancevalue2[0] = dataRaw.attribute(0).addStringValue("This is second string!");        instancevalue2[1] = 1;        dataRaw.add(new DenseInstance(1.0, instancevalue2));        System.out.println("After adding second instance");        System.out.println("--------------------------");        System.out.println(dataRaw);        System.out.println("--------------------------");    }}

其输出如下：

Before adding any instance--------------------------@relation TestInstances@attribute content string@attribute @@class@@ {A,B}@data--------------------------After adding a instance--------------------------@relation TestInstances@attribute content string@attribute @@class@@ {A,B}@data'This is a string!',A--------------------------After adding second instance--------------------------@relation TestInstances@attribute content string@attribute @@class@@ {A,B}@data'This is a string!',A'This is second string!',B--------------------------