weka get attribute from Instance - Java Machine Learning AI

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Description

weka get attribute from Instance

Demo Code

/*/*from www .  j  a  va 2 s .  c  o  m*/
 *  How to use WEKA API in Java 
 *  Copyright (C) 2014 
 *  @author Dr Noureddin M. Sadawi (noureddin.sadawi@gmail.com)
 *  
 *  This program is free software: you can redistribute it and/or modify
 *  it as you wish ... 
 *  I ask you only, as a professional courtesy, to cite my name, web page 
 *  and my YouTube Channel!
 *  
 */

package weka.api;

//import required classes
import weka.experiment.Stats;
import weka.core.AttributeStats;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.converters.ConverterUtils.DataSource;

public class AttInst {
    public static void main(String args[]) throws Exception {
        //load dataset
        DataSource source = new DataSource(
                "/home/likewise-open/ACADEMIC/csstnns/Desktop/weather.nominal.arff");
        //get instances object 
        Instances data = source.getDataSet();
        //set class index .. as the last attribute
        if (data.classIndex() == -1) {
            data.setClassIndex(data.numAttributes() - 1);
        }
        //get number of attributes (notice class is not counted)
        int numAttr = data.numAttributes() - 1;
        for (int i = 0; i < numAttr; i++) {
            //check if current attr is of type nominal
            if (data.attribute(i).isNominal()) {
                System.out.println("The " + i + "th Attribute is Nominal");
                //get number of values
                int n = data.attribute(i).numValues();
                System.out.println("The " + i + "th Attribute has: " + n
                        + " values");
            }

            //get an AttributeStats object
            AttributeStats as = data.attributeStats(i);
            int dC = as.distinctCount;
            System.out.println("The " + i + "th Attribute has: " + dC
                    + " distinct values");

            //get a Stats object from the AttributeStats
            if (data.attribute(i).isNumeric()) {
                System.out.println("The " + i + "th Attribute is Numeric");
                Stats s = as.numericStats;
                System.out.println("The " + i
                        + "th Attribute has min value: " + s.min
                        + " and max value: " + s.max + " and mean value: "
                        + s.mean);
            }
        }
        //get number of instances
        int numInst = data.numInstances();
        //loop through all instances
        for (int j = 0; j < numInst; j++) {
            //get the j'th instance
            Instance instance = data.instance(j);
            //check if 1st attr is missing from the j'th instance
            if (instance.isMissing(0)) {
                System.out.println("The " + 0 + "th Attribute is missing");
            }
            //check if the class is missing from the j'th instance
            if (instance.classIsMissing()) {
                System.out.println("The class is missing in the " + j
                        + "th Instance");
            }
            //if you want to access the value of Class in your data
            //notice classes of type nominal and string are given ID's
            double cV = instance.classValue();
            System.out.println(instance.classAttribute().value((int) cV));

        }

    }
}

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