\u7ed9\u5b9a\u4e00\u4e2a\u793e\u4ea4\u5173\u7cfb\uff08A,B\uff09\uff0cA\u548cB\u5206\u522b\u4ee3\u88682\u4e2a\u4eba\u7684id\u6216\u540d\u5b57\uff08\u5982\u679c\u662f\u540d\u5b57\uff0c\u8981\u6c42\u540d\u5b57\u4e0d\u80fd\u6709\u91cd\u590d\uff09\u3002\u8981\u6c42\u53ea\u4f7f\u7528\u4e00\u6b21MapReduce\uff0c\u8fc7\u6ee4\u6389\u91cc\u9762\u7684\u53cc\u5411\u5173\u7cfb\uff0c\u53ea\u4fdd\u7559\u5355\u5411\u5173\u7cfb\u3002\u6bd4\u5982\u73b0\u5728\u8fd9\u4e2a\u5173\u7cfb\u91cc\u5305\u542b\u5982\u4e0b\u5185\u5bb9\uff1a<\/p>\n
\uff08\u5f20\u4e09\uff0c\u674e\u56db\uff09<\/p>\n
\uff08\u5f20\u4e09\uff0c\u738b\u4e94\uff09<\/p>\n
\uff08\u5f20\u4e09\uff0c\u8d75\u516d\uff09<\/p>\n
\uff08\u674e\u56db\uff0c\u5f20\u4e09\uff09<\/p>\n
\u91cc\u9762\u7684\u7b2c1\u6761\u548c\u7b2c4\u6761\u6784\u6210\u4e86\u53cc\u5411\u5173\u7cfb\uff0c\u8981\u8fc7\u6ee4\u6389\uff0c\u5269\u4e0b\u7b2c2\u548c\u7b2c3\u6761\u3002<\/p>\n
\u601d\u8def1\uff1a\u5bf9\u6bcf\u4e00\u6761\u5173\u7cfb(A, B)\uff0c\u5728map\u9636\u6bb5\u751f\u6210(A, B) \u548c(B, A) \u3002\u5982\u679cA\u548cB\u662f\u53cc\u5411\u7684\uff0c\u4f1a\u751f\u62104\u6761\u8bb0\u5f55\uff0c\u5206\u522b\u662f\uff08A, B), \u00a0(B, A),\u00a0(B, A), (A,B)\u3002<\/p>\n
\u5728reduce\u9636\u6bb5\uff0c\u6211\u4eec\u53d1\u73b0key A\u5bf9\u5e94\u7684values\u91cc\uff0cB\u67092\u6761\u3002\u6211\u4eec\u77e5\u9053\u8fd9\u662f\u7531\u53cc\u5411\u5173\u7cfb\u4ea7\u751f\u7684\uff0c\u6211\u4eec\u4e0d\u5e94\u8be5\u6709\u4efb\u4f55\u8f93\u51fa\u3002\u6211\u4eec\u53ea\u8f93\u51fa\u5728values\u91cc\u53ea\u67091\u4e2a\u7684\u3002\u5047\u5982C\u5728values\u91cc\u53ea\u67091\u4e2a\u3002\u5219reduce\u9636\u6bb5\uff0c\u6211\u4eec\u8f93\u51fa(A,C)\u3002<\/p>\n
\u5e26\u6765\u7684\u95ee\u9898\uff1a\u4ee5\u4e0a\u7684\u529e\u6cd5\u80fd\u8fc7\u6ee4\u6389\u53cc\u5411\u5173\u7cfb\uff0c\u4f46\u662f\u4f1a\u8f93\u51fa\u591a\u4f59\u7684\u5185\u5bb9\u3002\u6bd4\u5982\u4e00\u4e2a\u5355\u9879\u5173\u7cfb (A, B)\u3002\u6309\u7167\u4ee5\u4e0a\u65b9\u6cd5\uff0c reduce\u9636\u6bb5\u6700\u540e\u4f1a\u8f93\u51fa(A,B)\u548c(B,A)\u3002\u5b9e\u9645\u4e0a\u4e0d\u5e94\u8be5\u8f93\u51fa(B, A)\u3002\u8fd9\u4e2a(B,A)\u662f\u6211\u4eec\u4eba\u4e3a\u52a0\u8fdb\u53bb\u7684\u3002<\/p>\n
\u601d\u8def2\uff1a\u5728\u601d\u8def1\u7684\u57fa\u7840\u4e0a\uff0cmap \u9636\u6bb5\u52a0\u5165\u6807\u8bb0\u3002\u5bf9\u6bcf\u4e00\u6761\u5173\u7cfb(A, B)\uff0c\u5728map\u9636\u6bb5\u751f\u6210(A, B|1) \u548c(B, A|0)\u30021\u4ee3\u8868\u771f\u5b9e\u5b58\u5728\u7684\u5173\u7cfb\uff0c0\u4ee3\u8868\u4e3a\u4e86\u89e3\u51b3\u95ee\u9898\u52a0\u5165\u7684\u865a\u6784\u5173\u7cfb\u3002\u5728reduce\u9636\u6bb5\uff0c\u6211\u4eec\u6309\u7167\u601d\u8def1\u8fc7\u6ee4\u6389\u67092\u4e2a\u503c\u7684\uff0c\u7136\u540e\u770b\u6807\u8bb0\u662f\u4e0d\u662f1\uff0c\u5982\u679c\u662f1\u5219\u8f93\u51fa\uff1b\u5982\u679c\u662f0\uff0c\u4e0d\u8f93\u51fa\u3002<\/p>\n
Hadoop MapReduce\u4ee3\u7801\u5982\u4e0b\uff1a
\n[code lang=”java”]
\nimport java.io.IOException;<\/p>\n
import org.apache.hadoop.io.LongWritable;
\nimport org.apache.hadoop.io.Text;
\nimport org.apache.hadoop.mapred.MapReduceBase;
\nimport org.apache.hadoop.mapred.Mapper;
\nimport org.apache.hadoop.mapred.OutputCollector;
\nimport org.apache.hadoop.mapred.Reporter;<\/p>\n
public class SingleRelationshipMapper extends MapReduceBase implements
\nMapper<LongWritable, Text, Text, Text>{<\/p>\n
@Override
\n public void map(LongWritable key, Text value, OutputCollector<Text, Text> output, Reporter arg3)
\n throws IOException {
\n String line = value.toString();
\n String[] names = line.split(" ");
\n Text text1 = new Text(names[0]);
\n Text text2 = new Text(names[1]);
\n output.collect(new Text(text1), new Text(text2+"|1")); \/\/1\u4ee3\u8868\u771f\u5b9e\u5173\u7cfb
\n output.collect(new Text(text2), new Text(text1+"|0")); \/\/0\u4ee3\u8868\u865a\u6784\u5173\u7cfb
\n }
\n}
\n[\/code]<\/p>\n
[code lang=”java”]<\/p>\n
import java.io.IOException;
\nimport java.util.ArrayList;
\nimport java.util.Iterator;
\nimport java.util.List;<\/p>\n
import org.apache.hadoop.io.Text;
\nimport org.apache.hadoop.mapred.MapReduceBase;
\nimport org.apache.hadoop.mapred.OutputCollector;
\nimport org.apache.hadoop.mapred.Reducer;
\nimport org.apache.hadoop.mapred.Reporter;<\/p>\n
public class SingleRelationshipReducer extends MapReduceBase implements
\n Reducer<Text, Text, Text, Text>{<\/p>\n
@Override
\n public void reduce(Text key, Iterator<Text> values, OutputCollector<Text, Text> output, Reporter arg3) throws IOException {
\n List<String> list = new ArrayList<String>();
\n while (values.hasNext()) {
\n list.add(values.next().toString());
\n }
\n for(String item:list){
\n String[] array = item.split("\\\\|");
\n if(onlyOne(array[0], list)){
\n if(array[1].equals("1")){
\n output.collect(key, new Text(array[0]));
\n }
\n }
\n }
\n }<\/p>\n
private boolean onlyOne(String str, List<String> list){
\n int count=0;
\n for(String item: list){
\n String array[] = item.split("\\\\|");
\n if(array[0].equals(str)){
\n count++;
\n }
\n }
\n return count==1;
\n }
\n}
\n[\/code]<\/p>\n
[code lang=”java”]
\nimport org.apache.hadoop.conf.Configured;
\nimport org.apache.hadoop.fs.Path;
\nimport org.apache.hadoop.io.Text;
\nimport org.apache.hadoop.mapred.FileInputFormat;
\nimport org.apache.hadoop.mapred.FileOutputFormat;
\nimport org.apache.hadoop.mapred.JobClient;
\nimport org.apache.hadoop.mapred.JobConf;
\nimport org.apache.hadoop.util.Tool;
\nimport org.apache.hadoop.util.ToolRunner;<\/p>\n
public class SingleRelationshipDriver extends Configured implements Tool{<\/p>\n
\/**
\n * @param args
\n * @throws Exception
\n *\/
\n public static void main(String[] args) throws Exception {
\n int exitCode = ToolRunner.run(new SingleRelationshipDriver(), args);
\n System.exit(exitCode);
\n }<\/p>\n
@Override
\n public int run(String[] arg) throws Exception {<\/p>\n
JobConf conf = new JobConf();
\n conf.setJobName("singleRelation");
\n conf.setJarByClass(SingleRelationshipDriver.class);
\n conf.setMapperClass(SingleRelationshipMapper.class);
\n conf.setReducerClass(SingleRelationshipReducer.class);
\n conf.setOutputKeyClass(Text.class);
\n conf.setOutputValueClass(Text.class);
\n FileInputFormat.addInputPaths(conf, arg[0]);
\n FileOutputFormat.setOutputPath(conf, new Path(arg[1]));
\n JobClient.runJob(conf);
\n return 0;
\n }<\/p>\n
}<\/p>\n
[\/code]<\/p>\n
\u8f93\u5165\uff1a<\/p>\n
John Tom
\nJohn Amily
\nJohn\u00a0George
\nAmily John<\/p>\n
\u8f93\u51fa\uff1a<\/p>\n
John Tom
\nJohn\u00a0George<\/p>\n","protected":false},"excerpt":{"rendered":"
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