数据挖掘贝叶斯.docx

数据挖掘贝叶斯(Bayes)算法java实现 注：本算法的实现仅仅适用于小规模数据集的实验与测试，不适合用于工程应用算法假定训练数据各属性列的值均是离散类型的。若是非离散类型的数据，需要首先进行数据的预处理，将非离散型的数据离散化。算法中使用到了DecimalCaculate类，该类是java中BigDecimal类的扩展，用于高精度浮点数的运算。该类的实现同本人转载的一篇博文：对BigDecimal常用方法的归类中的Arith类相同。算法实现的代码如下view plaincopy to clipboardprint?1. packageBayes;2. importjava.util.ArrayList;3. importjava.util.HashMap;4. importjava.util.Map;5. importutil.DecimalCalculate;6. /*7. *贝叶斯主体类8. *authorRowen9. *qq44377326410. *11. */luowen340512. *data2011.03.1513. */14. publicclassBayes15. /*16. *将原训练元组按类别划分17. *paramdatas训练元组18. *returnMap19. */20. MapString,ArrayListArrayListdatasOfClass(ArrayListArrayListdatas)21. MapString,ArrayListArrayListmap=newHashMapString,ArrayListArrayList();22. ArrayListt=null;23. Stringc=;24. for(inti=0;idatas.size();i+)25. t=datas.get(i);26. c=t.get(t.size()-1);27. if(map.containsKey(c)28. map.get(c).add(t);29. else30. ArrayListArrayListnt=newArrayListArrayList();31. nt.add(t);32. map.put(c,nt);33. 34. 35. returnmap;36. 37. 38. /*39. *在训练数据的基础上预测测试元组的类别40. *paramdatas训练元组41. *paramtestT测试元组42. *return测试元组的类别43. */44. publicStringpredictClass(ArrayListArrayListdatas,ArrayListtestT)45. MapString,ArrayListArrayListdoc=this.datasOfClass(datas);46. Objectclasses=doc.keySet().toArray();47. doublemaxP=0.00;48. intmaxPIndex=-1;49. for(inti=0;idoc.size();i+)50. Stringc=classesi.toString();51. ArrayListArrayListd=doc.get(c);52. doublepOfC=DecimalCalculate.div(d.size(),datas.size(),3);53. for(intj=0;jmaxP)58. maxP=pOfC;59. maxPIndex=i;60. 61. 62. returnclassesmaxPIndex.toString();63. 64. /*65. *计算指定属性列上指定值出现的概率66. *paramd属于某一类的训练元组67. *paramvalue列值68. *paramindex属性列索引69. *return概率70. */71. privatedoublepOfV(ArrayListArrayListd,Stringvalue,intindex)72. doublep=0.00;73. intcount=0;74. inttotal=d.size();75. ArrayListt=null;76. for(inti=0;itotal;i+)77. if(d.get(i).get(index).equals(value)78. count+;79. 80. 81. p=DecimalCalculate.div(count,total,3);82. returnp;83. 84. 算法测试类：view plaincopy to clipboardprint?1. packageBayes;2. importjava.io.BufferedReader;3. importjava.io.IOException;4. importjava.io.InputStreamReader;5. importjava.util.ArrayList;6. importjava.util.StringTokenizer;7. /*8. *贝叶斯算法测试类9. *authorRowen10. *qq44377326411. *12. */luowen340513. *data2011.03.1514. */15. publicclassTestBayes16. /*17. *读取测试元组18. *return一条测试元组19. *throwsIOException20. */21. publicArrayListreadTestData()throwsIOException22. ArrayListcandAttr=newArrayList();23. BufferedReaderreader=newBufferedReader(newInputStreamReader(System.in);24. Stringstr=;25. while(!(str=reader.readLine().equals()26. StringTokenizertokenizer=newStringTokenizer(str);27. while(tokenizer.hasMoreTokens()28. candAttr.add(tokenizer.nextToken();29. 30. 31. returncandAttr;32. 33. 34. /*35. *读取训练元组36. *return训练元组集合37. *throwsIOException38. */39. publicArrayListArrayListreadData()throwsIOException40. ArrayListArrayListdatas=newArrayListArrayList();41. BufferedReaderreader=newBufferedReader(newInputStreamReader(System.in);42. Stringstr=;43. while(!(str=reader.readLine().equals()44. StringTokenizertokenizer=newStringTokenizer(str);45. ArrayLists=newArrayList();46. while(tokenizer.hasMoreTokens()47. s.add(tokenizer.nextToken();48. 49. datas.add(s);50. 51. returndatas;52. 53. 54. publicstaticvoidmain(Stringargs)55. TestBayestb=newTestBayes();56. ArrayListArrayListdatas=null;57. ArrayListtestT=null;58. Bayesbayes=newBayes();59. try60. System.out.println(请输入训练数据);61. datas=tb.readData();62. while(true)63. System.out.println(请输入测试元组);64. testT=tb.readTestData();65. Stringc=bayes.predictClass(datas,testT);66. System.out.println(Theclassis:+c);67. 68. catch(IOExceptione)69. e.printStackTrace();70. 71. 72. 训练数据：view plaincopy to clipboardprint?1. youthhighnofairno2. youthhighnoexcellentno3. middle_agedhighnofairyes4. seniormediumnofairyes5. seniorlowyesfairyes6. seniorlowyesexcellentno7. middle_agedlowyesexcellentyes8. youthmediumnofairno9. youthlowyesfairyes10. seniormediumyesfairyes11. youthmediumyesexcellentyes12. middle_agedmediumnoexcellentyes13. middle_agedhighyesfairyes14. seniormediumnoexcellentno对原训练数据进行测试，测试如果如下：view plaincopy to clipboardprint?1. 请输入测试元组2. youthhighnofair3. Theclassis:no4. 请输入测试元组5. youthhighnoexcellent6. Theclassis:no7. 请输入测试元组8. middle_agedhighnofair9. Theclassis:yes10. 请输入测试元组11. seniormediumnofair12. Theclassis:yes13. 请输入测试元组14. seniorlowyesfair15. Theclassis:yes16. 请输入测试元组17. seniorlowyesexcellent18. Theclassis:yes19. 请输入测试元组20. middle_agedlowyesexcellent21. Theclassis:yes22. 请输入测试元组23. youthmediumnofair24. Theclassis:no25. 请输入测试元组26. youthlowyesfair27. Theclassis:yes28. 请输入测试元组29. seniormediumyesfair30. Theclassis:yes31. 请输入测试元组32. youthmediumyesexcellent33. Theclassis:yes34. 请输入测试元组35. middle_agedmediumnoexcellent36. Theclassis:yes37. 请输入测试元组38. middle_agedhighyesfair39. Theclassis:yes40. 请输入测试元组41. seniormediumnoexcellent42. Thecl