需求分析
需要對數據集進行預處理,選擇合適的特征進行聚類分析,確定聚類的數量和初始中心點,調用Mahout提供的K-Means算法進行聚類計算,評估聚類結果的準確性和穩定性。同時,需要對Mahout的使用和參數調優進行深入學習和實踐,以保證聚類結果的有效性和可靠性。
系統實現
? ? 1.對實驗整體的理解:
????本次實驗,我們的目的是理解聚類的原理,并且掌握常見聚類的算法,以及掌握使用Mahout實現K-Means聚類分析算法的過程。
? ? ?2.實驗整體流程分析:
- 創建項目,導入開發依賴包
- 編寫工具類
- 編寫聚類分析的代碼
- 將聚類結果輸出
- 評估聚類的效果
? ? ?3.準備工作:
- 使用IDEA創建一個Maven項目:mahout_kmeans_demo
?
- 修改pom.xml文件,導入開發MapReduce所需的Jar包
<dependencies><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-hdfs</artifactId><version>2.6.0</version></dependency><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-client</artifactId><version>2.6.0</version></dependency><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-common</artifactId><version>2.6.0</version></dependency><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-mapreduce-client-common</artifactId><version>2.6.0</version></dependency><dependency><groupId>org.apache.hadoop</groupId><artifactId>hadoop-mapreduce-client-core</artifactId><version>2.6.0</version></dependency><dependency><groupId>org.apache.mahout</groupId><artifactId>mahout-mr</artifactId><version>0.13.0</version></dependency><dependency><groupId>org.apache.mahout</groupId><artifactId>mahout-math</artifactId><version>0.13.0</version></dependency><dependency><groupId>org.apache.mahout</groupId><artifactId>mahout-hdfs</artifactId><version>0.13.0</version></dependency><dependency><groupId>org.apache.mahout</groupId><artifactId>mahout-integration</artifactId><version>0.13.0</version></dependency><dependency><groupId>org.apache.mahout</groupId><artifactId>mahout-examples</artifactId><version>0.13.0</version></dependency>
</dependencies>
下載相關依賴包
等待pom.xml文件不再出現錯誤即可?
- 準備實驗數據并下載
- 啟動Hadoop集群。
終端輸入start-all.sh
可以使用jps命令查看集群啟動情況。
? ? ?4.執行聚類過程:
- 編寫工具類HdfsUtil,對HDFS的基本操作進行封裝
package com;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.mapred.JobConf;import java.io.IOException;
import java.net.URI;public class HdfsUtil {private static final String HDFS = "hdfs://master:9000/";private String hdfsPath;private Configuration conf;public HdfsUtil(Configuration conf) {this(HDFS, conf);}public HdfsUtil(String hdfs, Configuration conf) {this.hdfsPath = hdfs;this.conf = conf;}public static JobConf config() {JobConf conf = new JobConf(HdfsUtil.class);conf.setJobName("HdfsDAO");return conf;}public void mkdirs(String folder) throws IOException {Path path = new Path(folder);FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);if (!fs.exists(path)) {fs.mkdirs(path);System.out.println("Create: " + folder);}fs.close();}public void rmr(String folder) throws IOException {Path path = new Path(folder);FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);fs.deleteOnExit(path);System.out.println("Delete: " + folder);fs.close();}public void ls(String folder) throws IOException {Path path = new Path(folder);FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);FileStatus[] list = fs.listStatus(path);System.out.println("ls: " + folder);System.out.println("==========================================================");for (FileStatus f : list) {System.out.printf("name: %s, folder: %s, size: %d\n", f.getPath(), f.isDir(), f.getLen());}System.out.println("==========================================================");fs.close();}public void createFile(String file, String content) throws IOException {FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);byte[] buff = content.getBytes();FSDataOutputStream os = null;try {os = fs.create(new Path(file));os.write(buff, 0, buff.length);System.out.println("Create: " + file);} finally {if (os != null)os.close();}fs.close();}public void copyFile(String local, String remote) throws IOException {FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);fs.copyFromLocalFile(new Path(local), new Path(remote));System.out.println("copy from: " + local + " to " + remote);fs.close();}public void download(String remote, String local) throws IOException {Path path = new Path(remote);FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);fs.copyToLocalFile(path, new Path(local));System.out.println("download: from" + remote + " to " + local);fs.close();}public void cat(String remoteFile) throws IOException {Path path = new Path(remoteFile);FileSystem fs = FileSystem.get(URI.create(hdfsPath), conf);FSDataInputStream fsdis = null;System.out.println("cat: " + remoteFile);try {fsdis = fs.open(path);IOUtils.copyBytes(fsdis, System.out, 4096, false);} finally {IOUtils.closeStream(fsdis);fs.close();}}
}
- 編寫KMeansMahout類,執行聚類過程
package com;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.mahout.clustering.Cluster;
import org.apache.mahout.clustering.canopy.CanopyDriver;
import org.apache.mahout.clustering.conversion.InputDriver;
import org.apache.mahout.clustering.kmeans.KMeansDriver;
import org.apache.mahout.common.HadoopUtil;
import org.apache.mahout.common.distance.EuclideanDistanceMeasure;
import org.apache.mahout.utils.clustering.ClusterDumper;public class KMeansMahout {private static final String HDFS = "hdfs://master:9000";public static void main(String[] args) throws Exception {String localFile = "/home/data/iris.dat";// mahout輸出至HDFS的目錄String outputPath = HDFS + "/user/hdfs/kmeans/output";// mahout的輸入目錄String inputPath = HDFS + "/user/hdfs/kmeans/input/";// canopy算法的t1和t2double t1 = 2;double t2 = 1;// 收斂閥值double convergenceDelta = 0.5;// 最大迭代次數int maxIterations = 10;Path output = new Path(outputPath);Path input = new Path(inputPath);Configuration conf = new Configuration();HdfsUtil hdfs = new HdfsUtil(HDFS, conf);hdfs.rmr(inputPath);hdfs.mkdirs(inputPath);hdfs.copyFile(localFile, inputPath);hdfs.ls(inputPath);// 每次執行聚類前,刪除掉上一次的輸出目錄HadoopUtil.delete(conf, output);// 執行聚類run(conf, input, output, new EuclideanDistanceMeasure(), t1, t2, convergenceDelta, maxIterations);}private static void run(Configuration conf, Path input, Path output,EuclideanDistanceMeasure euclideanDistanceMeasure, double t1, double t2,double convergenceDelta, int maxIterations) throws Exception {Path directoryContainingConvertedInput = new Path(output, "data");System.out.println("Preparing Input");// 將輸入文件序列化,并選取RandomAccessSparseVector作為保存向量的數據結構InputDriver.runJob(input, directoryContainingConvertedInput,"org.apache.mahout.math.RandomAccessSparseVector");System.out.println("Running Canopy to get initial clusters");// 保存canopy的目錄Path canopyOutput = new Path(output, "canopies");// 執行Canopy聚類CanopyDriver.run(conf, directoryContainingConvertedInput, canopyOutput,euclideanDistanceMeasure, t1, t2, false, 0.0, false);System.out.println("Running KMeans");// 執行k-means聚類,并使用canopy目錄KMeansDriver.run(conf, directoryContainingConvertedInput,new Path(canopyOutput, Cluster.INITIAL_CLUSTERS_DIR + "-final"),output, convergenceDelta, maxIterations, true, 0.0, false);System.out.println("run clusterdumper");// 將聚類的結果輸出至HDFSClusterDumper clusterDumper = new ClusterDumper(new Path(output, "clusters-*-final"),new Path(output, "clusteredPoints"));clusterDumper.printClusters(null);}
}
在KmeansMahout類上點擊右鍵并執行程序
?執行結果在HDFS目錄中
? ? ?5.解析聚類結果:
- 從Mahout的輸出目錄下提取出所要的信息
- 編寫ClusterOutput類,解析聚類后結果
package com;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.mahout.clustering.classify.WeightedPropertyVectorWritable;
import org.apache.mahout.math.Vector;import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;public class ClusterOutput {private static final String HDFS = "hdfs://master:9000";public static void main(String[] args) {try {// 需要被解析的mahout的輸出文件String clusterOutputPath = "/user/hdfs/kmeans/output";// 解析后的聚類結果,將輸出至本地磁盤String resultPath = "/home/data/result.txt";BufferedWriter bw;Configuration conf = new Configuration();conf.set("fs.default.name", HDFS);FileSystem fs = FileSystem.get(conf);SequenceFile.Reader reader = null;reader = new SequenceFile.Reader(fs, new Path(clusterOutputPath + "/clusteredPoints/part-m-00000"), conf);bw = new BufferedWriter(new FileWriter(new File(resultPath)));// key為聚簇中心IDIntWritable key = new IntWritable();WeightedPropertyVectorWritable value = new WeightedPropertyVectorWritable();while (reader.next(key, value)) {// 得到向量Vector vector = value.getVector();String vectorValue = "";// 將向量各個維度拼接成一行,用\t分隔for (int i = 0; i < vector.size(); i++) {if (i == vector.size() - 1) {vectorValue += vector.get(i);} else {vectorValue += vector.get(i) + "\t";}}bw.write(key.toString() + "\t" + vectorValue + "\n\n");}bw.flush();reader.close();} catch (Exception e) {e.printStackTrace();}}
}
在ClusterOutput類上右鍵執行程序
?執行結果被保存在/home/data/result.txt文件中,打開終端執行以下命令
? ? ?6.評估聚類效果:
- 編寫InterClusterDistances類,計算平均簇間距離
package com;import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.Writable;
import org.apache.mahout.clustering.Cluster;
import org.apache.mahout.clustering.iterator.ClusterWritable;
import org.apache.mahout.common.distance.DistanceMeasure;
import org.apache.mahout.common.distance.EuclideanDistanceMeasure;import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;public class InterClusterDistances {private static final String HDFS = "hdfs://master:9000";public static void main(String[] args) throws Exception {String inputFile = HDFS + "/user/hdfs/kmeans/output";System.out.println("聚類結果文件地址:" + inputFile);Configuration conf = new Configuration();Path path = new Path(inputFile + "/clusters-2-final/part-r-00000");System.out.println("Input Path:" + path);FileSystem fs = FileSystem.get(path.toUri(), conf);List<Cluster> clusters = new ArrayList<Cluster>();SequenceFile.Reader reader = new SequenceFile.Reader(fs, path, conf);Writable key = (Writable) reader.getKeyClass().newInstance();ClusterWritable value = (ClusterWritable) reader.getValueClass().newInstance();while (reader.next(key, value)) {Cluster cluster = value.getValue();clusters.add(cluster);value = (ClusterWritable) reader.getValueClass().newInstance();}System.out.println("Cluster In Total:" + clusters.size());DistanceMeasure measure = new EuclideanDistanceMeasure();double max = 0;double min = Double.MAX_VALUE;double sum = 0;int count = 0;Set<Double> total = new HashSet<Double>();// 如果聚類的個數大于1才開始計算if (clusters.size() != 1 && clusters.size() != 0) {for (int i = 0; i < clusters.size(); i++) {for (int j = 0; j < clusters.size(); j++) {double d = measure.distance(clusters.get(i).getCenter(), clusters.get(j).getCenter());min = Math.min(d, min);max = Math.max(d, max);total.add(d);sum += d;count++;}}System.out.println("Maximum Intercluster Distance:" + max);System.out.println("Minimum Intercluster Distance:" + min);System.out.println("Average Intercluster Distance:" + sum / count);for (double d : total) {System.out.print("[" + d + "] ");}} else if (clusters.size() == 1) {System.out.println("只有一個類,無法判斷聚類質量");} else if (clusters.size() == 0) {System.out.println("聚類失敗");}}
}
同樣右鍵執行程序,得到下圖結果