数据挖掘第三次实验报告Word格式文档下载.docx

数据挖掘第三次实验报告Word格式文档下载.docx

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*purposesandasarootclassforexperimentingon

*optimizations.

*

*InthelatestversiontheuseofDataHandlerisaddedforreading

*thedatabase.

*@authorMichaelHoller

*@version0.8,16.03.2004

*/

publicclassApriori{

intpass;

//numberofpasses

inttotal;

//totalnumberoffrequentitemsets

intminsup;

//minimalsupportofitemset

Stringfilename;

//thefilenameofthedatabase

Itemroot;

//therootitemoftheTrie

BufferedWriterwriter;

//thebuffertowritetheoutputto

DataHandlerdh;

//thehandlerforthedatabase

/**

*DefaultconstructurforcreatingaAprioriobject.

*/

publicApriori（）{

this.pass=0;

this.minsup=4;

this.dh=newDataHandler（"

test.dat"

）;

this.root=newItem（0）;

}

*ConstructurforcreatingaAprioriobjectwithparameters.

*@paramfilenamethenameofthedatabasefile

*@paramminsuptheminimalsupportthreshold

*@paramoutfilethenameoftheoutputfile

publicApriori（Stringfilename,intminsup,Stringoutfile）{

this.minsup=minsup;

this.dh=newDataHandler（filename）;

try{

if（!

outfile.equals（"

"

））{

writer=newBufferedWriter（newFileWriter（outfile））;

}catch（Exceptione）{}

*Thisoneisusedwithotherminingalgorithms.

*@paramdatahandlerthehandlerforthedatabase

publicApriori（intminsup,DataHandlerdatahandler）{

this.dh=datahandler;

*Theworkhorsemethodforthebasicimplementationof

*theApriorialgorithm.

publicvoidfindFrequentSets（）{

booleanrunning=true;

intcandidates=0,transactions=0,pruned=0,itemsets;

while（running）{

this.pass++;

candidates=this.generateCandidates（this.root,newVector（）,1）;

transactions=this.countSupport（）;

pruned=this.pruneCandidates（this.root）;

itemsets=candidates-pruned;

//correctthecandidatecountonfirstpassforprinting

if（this.pass==1）

candidates=total;

total+=itemsets;

if（itemsets<

=this.pass&

&

this.pass>

1）{

running=false;

}

System.out.println（"

pass:

"

+this.pass+

"

total:

+total+

candidates:

+candidates+

pruned:

+pruned）;

*Methodforgeneratingnewcandidates.

*Copiesthesiblingsofanitemtoitschildren.

*@paramitemtheitemtowhichgenerateditemsareadded

*@paramdepththedepthofrecursion

*@returnthenumberofnewcandidatesgenerated

publicintgenerateCandidates（Itemitem,Vectorcurrent,intdepth）{

Vectorv=item.getChildren（）;

Itemchild=item;

intgenerated=0;

for（Enumeratione=v.elements（）;

e.hasMoreElements（）;

）{

child=（Item）e.nextElement（）;

current.add（child）;

if（depth==this.pass-1）{

generated+=this.copySiblings（child,v,current）;

}else{

generated+=this.generateCandidates（child,current,depth+1）;

current.remove（child）;

returngenerated;

*MethodforcopyingthesiblingsofanItemtoitschildren.

*@paramitemtheitemtowhichthesiblingsarecopied

*@paramsiblingsthesiblingstobecopied

*@paramcurrentthecurrentitemsettobegenerated

*@returnthenumberofsiblingscopied

publicintcopySiblings（Itemitem,Vectorsiblings,Vectorcurrent）{

Enumeratione=siblings.elements（）;

Itemparent=item;

Itemsibling=newItem（）;

intcopied=0;

while（sibling.getLabel（）<

parent.getLabel（）&

e.hasMoreElements（））{

sibling=（Item）e.nextElement（）;

while（e.hasMoreElements（））{

current.add（sibling）;

if（this.pass<

=2||this.checkSubsets（current,this.root.getChildren（）,0,1））{

parent.addChild（newItem（sibling.getLabel（）））;

copied++;

current.remove（sibling）;

returncopied;

*Checksifthesubsetsoftheitemsettobegeneratedareallfrequent.

*@paramcurrentthecurrentitemsettobegenerated

*@paramchildrenthechildreninthetrieonthisdepth

*@parammarkthemarkinthecurrentitemset

*@paramdepthdepthofrecursion

*@returntrueifthesubsetsarefrequent,elsefalse

publicbooleancheckSubsets（Vectorcurrent,Vectorchildren,intmark,intdepth）{

booleanok=true;

Itemchild;

intindex;

inti=depth;

if（children==null）returnfalse;

while（ok&

（mark<

=i））{

index=children.indexOf（current.elementAt（i））;

if（index>

=0）{

if（depth<

this.pass-1）{

child=（Item）children.elementAt（index）;

ok=checkSubsets（current,child.getChildren（）,i+1,depth+1）;

ok=false;

i--;

returnok;

*Methodforcountingthesupportsofthecandidates

*generatedonthispass.

*@returnthenumberoftransactionsfromwhich

*thesupportwascounted

publicintcountSupport（）{

introwcount=0;

int[]items;

this.dh.open（）;

for（items=this.dh.read（）;

items.length>

0;

items=this.dh.read（））{

rowcount++;

if（this.pass==1）{

this.root.incSupport（）;

this.total+=generateFirstCandidates（items）;

countSupport（root,items,0,1）;

returnrowcount;

*Methodgeneratesthefirstcandidatesbyaddingeachitem

*foundinthedatabasetothechildrenoftherootitem.Also

*countsthesupportsoftheitemsfoundinthedatabase.

*@paramitemsthearrayofintegeritemsfromthedatabase

*@returnthenumberofcandidatesgenerated

publicintgenerateFirstCandidates（int[]items）{

Vectorv=root.getChildren（）;

Enumeratione=v.elements（）;

Itemitem=newItem（）;

for（inti=0;

i<

items.length;

i++）{

while（e.hasMoreElements（）&

item.getLabel（）<

items[i]）{

item=（Item）e.nextElement（）;

if（item.getLabel（）==items[i]）{

item.incSupport（）;

if（e.hasMoreElements（））

}elseif（item.getLabel（）>

intindex=v.indexOf（item）;

Itemchild=newItem（items[i]）;

child.incSupport（）;

this.root.addChild（child,index）;

generated++;

}else{

this.root.addChild（child）;

*AddsthecoveroftheItemgivenasparamaterandallthe

*ItemsinTriebelowit.

*@paramitemtheitemthecoverofwhichistobecounted

*@paramithepositioninthearray

*@paramdepththedepthofrecursion

publicvoidcountSupport（Itemitem,int[]items,inti,intdepth）{

inttmp;

//loopthroughthechildrentocheck

//break,ifthewholetransactionischecked

if（i==items.length）{break;

//doalinearsearchforthechildinthetransactionstartingfromi

tmp=i;

while（tmp<

items.length&

items[tmp]<

child.getLabel（））tmp++;

//ifthesameitemexists,increasesupportorgodeaper

if（tmp<

child.getLabel（）==items[tmp]）{

if（depth==this.pass）{

countSupport（child,items,tmp+1,depth+1）;

i=tmp+1;

*Methodforpruningthecandidates.Removesitemsthatare

*notfrequentfromtheTrie.

*@paramitemtheitemthechildrenofwhichwillbepruned

*@returnthenumberofitemsprunedfromthecandidates

publicintpruneCandidates（Itemitem）{

intpruned=0;

for（Enumeratione=newVector（v）.elements（）;

//checkinfrequency,existenceandthatitisfullycounted

if（child.getSupport（）<

this.minsup）{

v.remove（child）;

pruned++;

pruned+=pruneCandidates（child）;

returnpruned;

*Methodgetsandreturnstherootofthe

*candidatetrie.

*@returntherootofthecandidatetrie

publicItemgetTrie（）{

returnthis.root;

*Methodprintstheitemsetstothesystemoutputandtoafile

*ifthenameofanoutputfileexists.

publicvoidprintFrequentSets（）{

if（this.writer!

=null）{

print（root,"

\nnumberoffrequentitemsetsfound:

+this.total）;

*LoopsthroughtheTrierecursivelyadding

*pathsandsubpathstotheoutputstringalongtheway.

*@paramitemtheitemwheretherecursionis

*@paramstrthestringofthegatherditemset

publicvoidprint（Itemitem,Stringstr）{

this.writer.write（str+item.getLabel（）

+"

（"

+item.getSupport（）+"

）\n"

this.writer.flush（）;

}catch（Exceptionx）{

nooutputfile"

if（item.hasChildren（））{

print（item,str+item.getLabel（）+"