[java]? view plain ?copy ?print ?

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2. bf?ce?b?fg??
3. ah?bf?a?b?f??
4. be?ce?d??
5. a?bd?b?c?b?ade??

Sequence.java:

copy ? package?DataMining_PrefixSpan;??

??

import?java.util.ArrayList;??

/**?

?*?序列类?

?*??

?*?@author?lyq?

?*/??

public?class?Sequence?{??

????//?序列内的项集??

????private?ArrayList<ItemSet>?itemSetList;??

????public?Sequence()?{??

????????this.itemSetList?=?new?ArrayList<>();??

????}??

????public?ArrayList<ItemSet>?getItemSetList()?{??

????????return?itemSetList;??

????public?void?setItemSetList(ArrayList<ItemSet>?itemSetList)?{??

????????this.itemSetList?=?itemSetList;??

?????????*?判断单一项是否包含于此序列?

?????*??

?????*?@param?c?

?????*????????????待判断项?

?????*?@return?

?????*/??

????public?boolean?strIsContained(String?c)?{??

????????boolean?isContained?=?false;??

????????for?(ItemSet?itemSet?:?itemSetList)?{??

????????????isContained?=?false;??

??

????????????for?(String?s?:?itemSet.getItems())?{??

????????????????if?(itemSet.getItems().contains("_"))?{??

????????????????????continue;??

????????????????}??

????????????????if?(s.equals(c))?{??

????????????????????isContained?=?true;??

????????????????????break;??

????????????????}??

????????????}??

????????????if?(isContained)?{??

????????????????//?如果已经检测出包含了，直接挑出循环??

????????????????break;??

????????????}??

????????}??

????????return?isContained;??

????}??

/**?

?????*?判断组合项集是否包含于序列中?

?????*??

?????*?@param?itemSet?

?????*????????????组合的项集，元素超过1个?

?????*?@return?

?????*/??

????public?boolean?compoentItemIsContain(ItemSet?itemSet)?{??

????????boolean?isContained?=?false;??

????????ArrayList<String>?tempItems;??

????????String?lastItem?=?itemSet.getLastValue();??

????????for?(int?i?=?0;?i?<?this.itemSetList.size();?i++)?{??

????????????tempItems?=?this.itemSetList.get(i).getItems();??

????????????//?分2种情况查找，第一种从_X中找出x等于项集最后的元素，因为_前缀已经为原本的元素??

????????????if?(tempItems.size()?>?1?&&?tempItems.get(0).equals("_")??

????????????????????&&?tempItems.get(1).equals(lastItem))?{??

????????????????isContained?=?true;??

????????????????break;??

????????????}?else?if?(!tempItems.get(0).equals("_"))?{??

//?从没有_前缀的项集开始寻找，第二种为从后面的后缀中找出直接找出连续字符为ab为同一项集的项集??

????????????????if?(strArrayContains(tempItems,?itemSet.getItems()))?{??

????????}??

????????return?isContained;??

?????*?删除单个项?

?????*?@param?s?

?????*????????????待删除项?

????public?void?deleteSingleItem(String?s)?{??

????????ArrayList<String>?tempItems;??

????????ArrayList<String>?deleteItems?=?new?ArrayList<>();??

????????for?(ItemSet?itemSet?:?this.itemSetList)?{??

????????????tempItems?=?itemSet.getItems();??

????????????deleteItems?=?new?ArrayList<>();??

????????????for?(int?i?=?0;?i?<?tempItems.size();?i++)?{??

????????????????if?(tempItems.get(i).equals(s))?{??

????????????????????deleteItems.add(tempItems.get(i));??

????????????tempItems.removeAll(deleteItems);??

?????*?提取项s之后所得的序列?

?????*????????????目标提取项s?

????public?Sequence?extractItem(String?s)?{??

????????Sequence?extractSeq?=?this.copySeqence();??

????????ItemSet?itemSet;??

????????ArrayList<String>?items;??

????????ArrayList<ItemSet>?deleteItemSets?=?new?ArrayList<>();??

????????ArrayList<String>?tempItems?=?new?ArrayList<>();??

????????for?(int?k?=?0;?k?<?extractSeq.itemSetList.size();?k++)?{??

????????????itemSet?=?extractSeq.itemSetList.get(k);??

????????????items?=?itemSet.getItems();??

????????????if?(items.size()?==?1?&&?items.get(0).equals(s))?{??

//如果找到的是单项，则完全移除，跳出循环??

????????????????extractSeq.itemSetList.remove(k);??

????????????}?else?if?(items.size()?>?1?&&?!items.get(//在后续的多元素项中判断是否包含此元素??

????????????????if?(items.contains(s))?{??

????????????????????//如果包含把s后面的元素加入到临时字符数组中??

????????????????????int?index?=?items.indexOf(s);??

????????????????????for?(int?j?=?index;?j?<?items.size();?j++)?{??

????????????????????????tempItems.add(items.get(j));??

????????????????????}??

????????????????????//将第一位的s变成下标符"_"??

????????????????????tempItems.set(0,?"_");??

????????????????????if?(tempItems.size()?==?1)?{??

????????????????????????//?如果此匹配为在最末端，同样移除??

????????????????????????deleteItemSets.add(itemSet);??

????????????????????}?else?{??

????????????????????????//将变化后的项集替换原来的??

????????????????????????extractSeq.itemSetList.set(k,?new?ItemSet(tempItems));??

????????????????????}??

????????????????????break;??

????????????????}?else?{??

????????????????????deleteItemSets.add(itemSet);??

????????????}?else?{??

????????????????//?不符合以上2项条件的统统移除??

????????????????deleteItemSets.add(itemSet);??

????????extractSeq.itemSetList.removeAll(deleteItemSets);??

????????return?extractSeq;??

?????*?提取组合项之后的序列?

?????*?@param?array?

?????*????????????组合数组?

????public?Sequence?extractCompoentItem(ArrayList<String>?array)?{??

????????//?找到目标项，是否立刻停止??

????????boolean?stopExtract?=?false;??

????????Sequence?seq?=?this.copySeqence();??

????????String?lastItem?=?array.get(array.size()?-?1);??

????????ArrayList<ItemSet>?deleteItems?=?new?ArrayList<>();??

????????for?(int?i?=?0;?i?<?seq.itemSetList.size();?i++)?{??

????????????if?(stopExtract)?{??

????????????tempItems?=?seq.itemSetList.get(i).getItems();??

????????????//?分2种情况查找，第一种从_X中找出x等于项集最后的元素，因为_前缀已经为原本的元素??

????????????if?(tempItems.size()?>?0).equals("_")??

????????????????????&&?tempItems.get(1).equals(lastItem))?{??

????????????????if?(tempItems.size()?==?2)?{??

????????????????????seq.itemSetList.remove(i);??

????????????????}?else?{??

//?把1号位置变为下标符"_"，往后移1个字符的位置??

1,0); background-color:inherit">//?移除第一个的"_"下划符??

????????????????????tempItems.remove(0);??

????????????????stopExtract?=?true;??

????????????}?else?if?(!tempItems.get(0).equals("_"))?{??

//?从没有_前缀的项集开始寻找，第二种为从后面的后缀中找出直接找出连续字符为ab为同一项集的项集??

????????????????if?(strArrayContains(tempItems,?array))?{??

//?从左往右找出第一个给定字符的位置，把后面的部分截取出来??

????????????????????int?index?=?tempItems.indexOf(lastItem);??

????????????????????ArrayList<String>?array2?=?new?ArrayList<String>();??

????????????????????for?(int?j?=?index;?j?<?tempItems.size();?j++)?{??

????????????????????????array2.add(tempItems.get(j));??

????????????????????array2.set( ????????????????????if?(array2.size()?==?1)?{??

//如果此项在末尾的位置，则移除该项，否则进行替换??

????????????????????????deleteItems.add(seq.itemSetList.get(i));??

????????????????????}?else?{??

????????????????????????seq.itemSetList.set(i,?new?ItemSet(array2));??

????????????????????stopExtract?=?true;??

????????????????????deleteItems.add(seq.itemSetList.get(i));??

????????????}?else?{??

//?这种情况是处理_X中X不等于最后一个元素的情况??

????????????????deleteItems.add(seq.itemSetList.get(i));??

??????????

????????seq.itemSetList.removeAll(deleteItems);??

????????return?seq;??

?????*?深拷贝一个序列?

????public?Sequence?copySeqence()?{??

????????Sequence?copySeq?=?new?Sequence();??

????????ItemSet?tempItemSet;??

????????for?(ItemSet?itemSet?:?this.itemSetList)?{??

????????????items?=?(ArrayList<String>)?itemSet.getItems().clone();??

????????????tempItemSet?=?new?ItemSet(items);??

????????????copySeq.getItemSetList().add(tempItemSet);??

????????return?copySeq;??

?????*?获取序列中最后一个项集的最后1个元素?

????public?String?getLastItemSetValue()?{??

????????int?size?=?this.getItemSetList().size();??

????????ItemSet?itemSet?=?this.getItemSetList().get(size?-?1);??

????????size?=?itemSet.getItems().size();??

????????return?itemSet.getItems().get(size?-??????*?判断strList2是否是strList1的子序列?

?????*?@param?strList1?

?????*?@param?strList2?

????public?boolean?strArrayContains(ArrayList<String>?strList1,??

????????????ArrayList<String>?strList2)?{??

0;?i?<?strList1.size()?-?strList2.size()?+?1;?i++)?{??

????????????isContained?=?true;??

????????????for?(int?j?=?

????????????????if?(!strList1.get(k).equals(strList2.get(j)))?{??

????????????????????isContained?=?false;??

}??

ItemSet.java：

copy ??*?字符项集类?

public?class?ItemSet?{??

//?项集内的字符??

????private?ArrayList<String>?items;??

????public?ItemSet(String[]?str)?{??

????????items?=?new?ArrayList<>();??

????????for?(String?s?:?str)?{??

????????????items.add(s);??

????public?ItemSet(ArrayList<String>?itemsList)?{??

????????this.items?=?itemsList;??

????public?ItemSet(String?s)?{??

????????items?=?new?ArrayList<>();??

0;?i?<?s.length();?i++)?{??

????????????items.add(s.charAt(i)?+?"");??

????public?ArrayList<String>?getItems()?{??

????????return?items;??

????public?void?setItems(ArrayList<String>?items)?{??

????????this.items?=?items;??

?????*?获取项集最后1个元素?

????public?String?getLastValue()?{??

????????int?size?=?this.items.size();??

????????return?this.items.get(size?-? }??

PrefixSpanTool.java：

copy ? import?java.io.BufferedReader;??

import?java.io.File;??

import?java.io.FileReader;??

import?java.io.IOException;??

import?java.util.Collections;??

import?java.util.HashMap;??

import?java.util.Map;??

?*?PrefixSpanTool序列模式分析算法工具类?

?*??

?*?@author?lyq?

?*/??

public?class?PrefixSpanTool?{??

//?测试数据文件地址??

????private?String?filePath;??

//?最小支持度阈值比例??

????private?double?minSupportRate;??

//?最小支持度，通过序列总数乘以阈值比例计算??

????private?int?minSupport;??

//?原始序列组??

????private?ArrayList<Sequence>?totalSeqs;??

//?挖掘出的所有序列频繁模式??

????private?ArrayList<Sequence>?totalFrequentSeqs;??

//?所有的单一项，用于递归枚举??

????private?ArrayList<String>?singleItems;??

????public?PrefixSpanTool(String?filePath,?double?minSupportRate)?{??

????????this.filePath?=?filePath;??

????????this.minSupportRate?=?minSupportRate;??

????????readDataFile();??

?????*?从文件中读取数据?

????private?void?readDataFile()?{??

????????File?file?=?new?File(filePath);??

????????ArrayList<String[]>?dataArray?=?new?ArrayList<String[]>();??

????????try?{??

????????????BufferedReader?in?=?new?BufferedReader(new?FileReader(file));??

????????????String?str;??

????????????String[]?tempArray;??

????????????while?((str?=?in.readLine())?!=?null)?{??

????????????????tempArray?=?str.split("?");??

????????????????dataArray.add(tempArray);??

????????????in.close();??

????????}?catch?(IOException?e)?{??

????????????e.getStackTrace();??

????????minSupport?=?(int)?(dataArray.size()?*?minSupportRate);??

????????totalSeqs?=?new?ArrayList<>();??

????????totalFrequentSeqs?=?new?ArrayList<>();??

????????Sequence?tempSeq;??

????????ItemSet?tempItemSet;??

????????for?(String[]?str?:?dataArray)?{??

????????????tempSeq?=?new?Sequence();??

????????????for?(String?s?:?str)?{??

????????????????tempItemSet?=?new?ItemSet(s);??

????????????????tempSeq.getItemSetList().add(tempItemSet);??

????????????totalSeqs.add(tempSeq);??

????????System.out.println("原始序列数据：");??

????????outputSeqence(totalSeqs);??

?????*?输出序列列表内容?

?????*?@param?seqList?

?????*????????????待输出序列列表?

????private?void?outputSeqence(ArrayList<Sequence>?seqList)?{??

????????for?(Sequence?seq?:?seqList)?{??

????????????System.out.print("<");??

????????????for?(ItemSet?itemSet?:?seq.getItemSetList())?{??

????????????????if?(itemSet.getItems().size()?>? ????????????????????System.out.print("(");??

????????????????for?(String?s?:?itemSet.getItems())?{??

????????????????????System.out.print(s?+?"?");??

????????????????????System.out.print(")");??

????????????System.out.println(">");??

?????*?移除初始序列中不满足最小支持度阈值的单项?

????private?void?removeInitSeqsItem()?{??

????????int?count?=?0;??

????????HashMap<String,?Integer>?itemMap?=?new?HashMap<>();??

????????singleItems?=?new?ArrayList<>();??

????????for?(Sequence?seq?:?totalSeqs)?{??

????????????????????if?(!itemMap.containsKey(s))?{??

????????????????????????itemMap.put(s,? ????????String?key;??

????????for?(Map.Entry?entry?:?itemMap.entrySet())?{??

????????????count?=? ????????????key?=?(String)?entry.getKey();??

????????????for?(Sequence?seq?:?totalSeqs)?{??

????????????????if?(seq.strIsContained(key))?{??

????????????????????count++;??

????????????itemMap.put(key,?count);??

????????for?(Map.Entry?entry?:?itemMap.entrySet())?{??

????????????count?=?(int)?entry.getValue();??

????????????if?(count?<?minSupport)?{??

//?如果支持度阈值小于所得的最小支持度阈值，则删除该项??

????????????????for?(Sequence?seq?:?totalSeqs)?{??

????????????????????seq.deleteSingleItem(key);??

????????????????singleItems.add(key);??

????????Collections.sort(singleItems);??

?????*?递归搜索满足条件的序列模式?

?????*?@param?beforeSeq?

?????*????????????前缀序列?

?????*?@param?afterSeqList?

?????*????????????后缀序列列表?

????private?void?recursiveSearchSeqs(Sequence?beforeSeq,248)"> ????????????ArrayList<Sequence>?afterSeqList)?{??

????????Sequence?tempSeq2;??

????????ArrayList<Sequence>?tempSeqList?=?new?ArrayList<>();??

????????for?(String?s?:?singleItems)?{??

//?分成2种形式递归，以<a>为起始项，第一种直接加入独立项集遍历<a,a>,<a,b>?<a,c>..??

????????????if?(isLargerThanMinSupport(s,?afterSeqList))?{??

????????????????tempSeq?=?beforeSeq.copySeqence();??

????????????????totalFrequentSeqs.add(tempSeq);??

????????????????tempSeqList?=?new?ArrayList<>();??

????????????????for?(Sequence?seq?:?afterSeqList)?{??

????????????????????if?(seq.strIsContained(s))?{??

????????????????????????tempSeq2?=?seq.extractItem(s);??

????????????????????????tempSeqList.add(tempSeq2);??

????????????????recursiveSearchSeqs(tempSeq,?tempSeqList);??

//?第二种递归为以元素的身份加入最后的项集内以a为例<(aa)>,<(ab)>,<(ac)>...??

//?a在这里可以理解为一个前缀序列，里面可能是单个元素或者已经是多元素的项集??

????????????tempSeq?=?beforeSeq.copySeqence();??

????????????int?size?=?tempSeq.getItemSetList().size();??

????????????tempItemSet?=?tempSeq.getItemSetList().get(size?-? ????????????tempItemSet.getItems().add(s);??

????????????if?(isLargerThanMinSupport(tempItemSet,?afterSeqList))?{??

????????????????tempSeqList?=?new?ArrayList<>();??

????????????????for?(Sequence?seq?:?afterSeqList)?{??

????????????????????if?(seq.compoentItemIsContain(tempItemSet))?{??

????????????????????????tempSeq2?=?seq.extractCompoentItem(tempItemSet??

????????????????????????????????.getItems());??

????????????????totalFrequentSeqs.add(tempSeq);??

????????????????recursiveSearchSeqs(tempSeq,?tempSeqList);??

?????*?所传入的项组合在所给定序列中的支持度是否超过阈值?

?????*????????????所需匹配的项?

?????*?@param?seqList?

?????*????????????比较序列数据?

????private?boolean?isLargerThanMinSupport(String?s,?ArrayList<Sequence>?seqList)?{??

????????boolean?isLarge?=?false;??

????????for?(Sequence?seq?:?seqList)?{??

????????????if?(seq.strIsContained(s))?{??

????????????????count++;??

????????if?(count?>=?minSupport)?{??

????????????isLarge?=?true;??

????????return?isLarge;??

?????*?所传入的组合项集在序列中的支持度是否大于阈值?

?????*?@param?itemSet?

?????*????????????组合元素项集?

?????*????????????比较的序列列表?

????private?boolean?isLargerThanMinSupport(ItemSet?itemSet,??

????????????ArrayList<Sequence>?seqList)?{??

????????boolean?isLarge?=?false;??

????????int?count?=?0;??

????????if?(seqList?==?null)?{??

????????????return?false;??

????????????if?(seq.compoentItemIsContain(itemSet))?{??

????????????????count++;??

????????if?(count?>=?minSupport)?{??

????????????isLarge?=?true;??

????????return?isLarge;??

?????*?序列模式分析计算?

????public?void?prefixSpanCalculate()?{??

????????Sequence?seq;??

????????removeInitSeqsItem();??

//?从最开始的a,d开始递归往下寻找频繁序列模式??

????????????seq?=?new?Sequence();??

????????????itemSet?=?new?ItemSet(s);??

????????????seq.getItemSetList().add(itemSet);??

????????????????for?(Sequence?s2?:?totalSeqs)?{??

//?判断单一项是否包含于在序列中，包含才进行提取操作??

????????????????????if?(s2.strIsContained(s))?{??

????????????????????????tempSeq?=?s2.extractItem(s);??

????????????????????????tempSeqList.add(tempSeq);??

????????????????totalFrequentSeqs.add(seq);??

????????????????recursiveSearchSeqs(seq,153); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> ????????printTotalFreSeqs();??

?????*?按模式类别输出频繁序列模式?

????private?void?printTotalFreSeqs()?{??

????????System.out.println("序列模式挖掘结果：");??

??????????

????????ArrayList<Sequence>?seqList;??

????????????seqList?=?new?ArrayList<>();??

????????????for?(Sequence?seq?:?totalFrequentSeqs)?{??

????????????????if?(seq.getItemSetList().get(0).getItems().get( ????????????????????seqList.add(seq);??

????????????seqMap.put(s,?seqList);??

????????for?(String?s?:?singleItems)?{??

????????????System.out.println();??

????????????System.out.println();??

????????????seqList?=?(ArrayList<Sequence>)?seqMap.get(s);??

????????????for?(Sequence?tempSeq?:?seqList)?{??

????????????????System.out.print("<");??

????????????????for?(ItemSet?itemSet?:?tempSeq.getItemSetList())?{??

????????????????????if?(itemSet.getItems().size()?>? ????????????????????????System.out.print("(");??

????????????????????for?(String?str?:?itemSet.getItems())?{??

????????????????????????System.out.print(str?+?"?");??

????????????????????????System.out.print(")");??

????????????????System.out.print(">,?");??

//?每5个序列换一行??

????????????????if?(count?==?5)?{??

????????????????????count?=? ????????????????????System.out.println();??

}??

调用类Client.java:

copy ??*?PrefixSpan序列模式挖掘算法?

?*?

public?class?Client?{??

????public?static?void?main(String[]?agrs){??

????????String?filePath?=?"C:UserslyqDesktopiconinput.txt";??

????????//最小支持度阈值率??

????????double?minSupportRate?=?0.4;??

????????PrefixSpanTool?tool?=?new?PrefixSpanTool(filePath,?minSupportRate);??

????????tool.prefixSpanCalculate();??

}??

输出的结果：

copy ? 原始序列数据：??

<(b?d?)c?b?(a?c?)>??

<(b?f?)(c?e?)b?(f?g?)>??

<(a?h?)(b?f?)a?b?f?>??

<(b?e?)(c?e?)d?>??

<a?(b?d?)b?c?b?(a?d?e?)>??

序列模式挖掘结果：??

<a?>,?<a?a?>,?<a?b?>,?<a?b?a?>,?<a?b?b?>,???

<b?>,?<b?a?>,?<b?b?>,?<b?b?a?>,?<b?b?c?>,???

<b?b?f?>,?<b?c?>,?<b?c?a?>,?<b?c?b?>,?<b?c?b?a?>,153); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <b?c?d?>,?<b?(c?e?)>,?<b?d?>,?<(b?d?)>,?<(b?d?)a?>,248)"> <(b?d?)b?>,?<(b?d?)b?a?>,?<(b?d?)b?c?>,?<(b?d?)c?>,?<(b?d?)c?a?>,153); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <(b?d?)c?b?>,?<(b?d?)c?b?a?>,?<b?e?>,?<b?f?>,?<(b?f?)>,248)"> <(b?f?)b?>,?<(b?f?)b?f?>,?<(b?f?)f?>,248)"> <c?>,?<c?a?>,?<c?b?>,?<c?b?a?>,?<c?d?>,153); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <(c?e?)>,153); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <d?>,?<d?a?>,?<d?b?>,?<d?b?a?>,?<d?b?c?>,248)"> <d?c?>,?<d?c?a?>,?<d?c?b?>,?<d?c?b?a?>,248)"> <e?>,248)"> <f?>,?<f?b?>,?<f?b?f?>,?<f?f?>,???

经过比对，与上述表格中的结果完全一致，从结果中可以看出他的递归顺序正是刚刚我所想要的那种。

算法实现时的难点

我在实现这个算法时确实碰到了不少的问题，下面一一列举。

1、Sequence序列在判断或者提取单项和组合项的时候，情况少考虑了，还有考虑到了处理的方式又可能错了。

2、递归的顺序在最早的时候考虑错了，后来对递归的顺序进行了调整。

3、在算法的调试时遇到了，当发现某一项出现问题时，不能够立即调试，因为里面陷入的递归层次实在太深，只能自己先手算此情况下的前缀，后缀序列，然后自己模拟出1个Seq调试，在纠正extract方法时用的比较多。

我对PrefixSpan算法的理解

实现了这个算法之后，再回味这个算法，还是很奇妙的，一个序列，通过从左往右的扫描，通过各个项集的子集，能够组合出许许多多的的序列模式，然后进行挖掘，PrefixSpan通过递归的形式全部找出，而且效率非常高，的确是个很强大的算法。

PrefixSpan算法整体的特点

首先一点，他不会产生候选序列，在产生投影数据库的时候(也就是产生后缀子序列),他的规模是不断减小的。PrefixSpan采用分治法进行序列的挖掘，十分的高效。唯一比较会有影响的开销就是在构造后缀子序列的过程，专业上的名称叫做构造投影数据库的时候。

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