應該場景:
有一批酒店的產品名字,名字不規則,有中文有英文也會有特殊符號,現需要按這個產品的名稱將其對應到相應的房型上。這時就需要按字符進行比較。去匹配相似度最高的房型名稱之上。經過對數據的分析,最後有中文的名稱採用分詞的方法進行相似對比,英文的文本之間的相似度計算用的是餘弦距離,先哈希過。下面是計算兩個List的餘弦距離。
英文字符進行相似度比較
package com.e100.hotelcore.stringUtils;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
public class EnStringCompare {
public static double getSimilarity(ArrayList<String> doc1, ArrayList<String> doc2) {
if (doc1 != null && doc1.size() > 0 && doc2 != null && doc2.size() > 0) {
Map<Long, int[]> AlgorithmMap = new HashMap<Long, int[]>();
for (int i = 0; i < doc1.size(); i++) {
String d1 = doc1.get(i);
long sIndex = hashId(d1);
int[] fq = AlgorithmMap.get(sIndex);
if (fq != null) {
fq[0]++;
} else {
fq = new int[2];
fq[0] = 1;
fq[1] = 0;
AlgorithmMap.put(sIndex, fq);
}
}
for (int i = 0; i < doc2.size(); i++) {
String d2 = doc2.get(i);
long sIndex = hashId(d2);
int[] fq = AlgorithmMap.get(sIndex);
if (fq != null) {
fq[1]++;
} else {
fq = new int[2];
fq[0] = 0;
fq[1] = 1;
AlgorithmMap.put(sIndex, fq);
}
}
Iterator<Long> iterator = AlgorithmMap.keySet().iterator();
double sqdoc1 = 0;
double sqdoc2 = 0;
double denominator = 0;
while (iterator.hasNext()) {
int[] c = AlgorithmMap.get(iterator.next());
denominator += c[0] * c[1];
sqdoc1 += c[0] * c[0];
sqdoc2 += c[1] * c[1];
}
return denominator / Math.sqrt(sqdoc1 * sqdoc2);
} else {
return 0;
}
}
public static long hashId(String s) {
long seed = 131; // 31 131 1313 13131 131313 etc.. BKDRHash
long hash = 0;
for (int i = 0; i < s.length(); i++) {
hash = (hash * seed) + s.charAt(i);
}
return hash;
}
public static void main(String[] args) {
ArrayList<String> t1 = new ArrayList<String>();
ArrayList<String> t2 = new ArrayList<String>();
ArrayList<String> t3 = new ArrayList<String>();
t1.add("double");
t1.add("or");
t1.add("twin");
t1.add("superior");
t2.add("superior");
t2.add("twin");
t2.add("double");
t3.add("superior");
t3.add("suite");
t3.add("standard");
t3.add("zone");
System.out.println(getSimilarity(t1, t2));
System.out.println(getSimilarity(t1, t3));
}
}
餘弦相似度計算字符串相似率
比較中文比較準確,英文區分大少寫,按空格分詞,空格的多少也會影響到相似度,所以上面的方法比較英文比較準確。
1、pom.xml
展示一些主要的jar包
<!--結合操作工具包-->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.5</version>
</dependency>
<!--bean實體註解工具包-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<!--漢語言包,主要用於分詞-->
<dependency>
<groupId>com.hankcs</groupId>
<artifactId>hanlp</artifactId>
<version>portable-1.6.5</version>
</dependency>
2、main方法
public static void main(String[] args) {
String content1 = "run of the house";
String content2 = "1 bed presidential suite space zone";
String content3 = "Premier";
String content4 = "Superior";
double score = CosineSimilarity.getSimilarity(content1, content2);
System.out.println("相似度:" + score);
score = CosineSimilarity.getSimilarity(content1, content3);
System.out.println("相似度:" + score);
score = CosineSimilarity.getSimilarity(content1, content4);
System.out.println("相似度:" + score);
}
3、Tokenizer(分詞工具類)
package com.e100.hotelcore.stringUtils;
import com.hankcs.hanlp.HanLP;
import com.hankcs.hanlp.seg.common.Term;
import java.util.List;
import java.util.stream.Collectors;
/**
* 中文分詞工具類*/
public class Tokenizer {
/**
* 分詞*/
public static List<Word> segment(String sentence) {
//1、 採用HanLP中文自然語言處理中標準分詞進行分詞
List<Term> termList = HanLP.segment(sentence);
//上面控制檯打印信息就是這裏輸出的
System.out.println(termList.toString());
//2、重新封裝到Word對象中(term.word代表分詞後的詞語,term.nature代表改詞的詞性)
return termList.stream().map(term -> new Word(term.word, term.nature.toString())).collect(Collectors.toList());
}
}
4、Word(封裝分詞結果)
package com.e100.hotelcore.stringUtils;
import lombok.Data;
import java.util.Objects;
/**
* 封裝分詞結果*/
@Data
public class Word implements Comparable {
// 詞名
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
// 詞性
private String pos;
// 權重,用於詞向量分析
private Float weight;
public Word(String name, String pos) {
this.name = name;
this.pos = pos;
}
@Override
public int hashCode() {
return Objects.hashCode(this.name);
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Word other = (Word) obj;
return Objects.equals(this.name, other.name);
}
@Override
public String toString() {
StringBuilder str = new StringBuilder();
if (name != null) {
str.append(name);
}
if (pos != null) {
str.append("/").append(pos);
}
return str.toString();
}
@Override
public int compareTo(Object o) {
if (this == o) {
return 0;
}
if (this.name == null) {
return -1;
}
if (o == null) {
return 1;
}
if (!(o instanceof Word)) {
return 1;
}
String t = ((Word) o).getName();
if (t == null) {
return 1;
}
return this.name.compareTo(t);
}
public Float getWeight() {
return weight;
}
public void setWeight(Float weight) {
this.weight = weight;
}
}
5、CosineSimilarity
package com.e100.hotelcore.stringUtils;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.CollectionUtils;
import java.math.BigDecimal;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
/**
* 判定方式:餘弦相似度,通過計算兩個向量的夾角餘弦值來評估他們的相似度 餘弦夾角原理: 向量a=(x1,y1),向量b=(x2,y2)
* similarity=a.b/|a|*|b| a.b=x1x2+y1y2
* |a|=根號[(x1)^2+(y1)^2],|b|=根號[(x2)^2+(y2)^2]
*/
public class CosineSimilarity {
protected static final Logger LOGGER = LoggerFactory.getLogger(CosineSimilarity.class);
/**
* 1、計算兩個字符串的相似度
*/
public static double getSimilarity(String text1, String text2) {
// 如果wei空,或者字符長度爲0,則代表完全相同
if (StringUtils.isBlank(text1) && StringUtils.isBlank(text2)) {
return 1.0;
}
// 如果一個爲0或者空,一個不爲,那說明完全不相似
if (StringUtils.isBlank(text1) || StringUtils.isBlank(text2)) {
return 0.0;
}
// 這個代表如果兩個字符串相等那當然返回1了(這個我爲了讓它也分詞計算一下,所以註釋掉了)
// if (text1.equalsIgnoreCase(text2)) {
// return 1.0;
// }
// 第一步:進行分詞
List<Word> words1 = Tokenizer.segment(text1);
List<Word> words2 = Tokenizer.segment(text2);
return getSimilarity(words1, words2);
}
/**
* 2、對於計算出的相似度保留小數點後六位
*/
public static double getSimilarity(List<Word> words1, List<Word> words2) {
double score = getSimilarityImpl(words1, words2);
// (int) (score * 1000000 + 0.5)其實代表保留小數點後六位
// ,因爲1034234.213強制轉換不就是1034234。對於強制轉換添加0.5就等於四捨五入
score = (int) (score * 1000000 + 0.5) / (double) 1000000;
return score;
}
/**
* 文本相似度計算 判定方式:餘弦相似度,通過計算兩個向量的夾角餘弦值來評估他們的相似度 餘弦夾角原理: 向量a=(x1,y1),向量b=(x2,y2) similarity=a.b/|a|*|b| a.b=x1x2+y1y2
* |a|=根號[(x1)^2+(y1)^2],|b|=根號[(x2)^2+(y2)^2]
*/
public static double getSimilarityImpl(List<Word> words1, List<Word> words2) {
// 向每一個Word對象的屬性都注入weight(權重)屬性值
taggingWeightByFrequency(words1, words2);
//第二步:計算詞頻
//通過上一步讓每個Word對象都有權重值,那麼在封裝到map中(key是詞,value是該詞出現的次數(即權重))
Map<String, Float> weightMap1 = getFastSearchMap(words1);
Map<String, Float> weightMap2 = getFastSearchMap(words2);
//將所有詞都裝入set容器中
Set<Word> words = new HashSet<>();
words.addAll(words1);
words.addAll(words2);
AtomicFloat ab = new AtomicFloat();// a.b
AtomicFloat aa = new AtomicFloat();// |a|的平方
AtomicFloat bb = new AtomicFloat();// |b|的平方
// 第三步:寫出詞頻向量,後進行計算
words.parallelStream().forEach(word -> {
//看同一詞在a、b兩個集合出現的此次
Float x1 = weightMap1.get(word.getName());
Float x2 = weightMap2.get(word.getName());
if (x1 != null && x2 != null) {
//x1x2
float oneOfTheDimension = x1 * x2;
//+
ab.addAndGet(oneOfTheDimension);
}
if (x1 != null) {
//(x1)^2
float oneOfTheDimension = x1 * x1;
//+
aa.addAndGet(oneOfTheDimension);
}
if (x2 != null) {
//(x2)^2
float oneOfTheDimension = x2 * x2;
//+
bb.addAndGet(oneOfTheDimension);
}
});
//|a| 對aa開方
double aaa = Math.sqrt(aa.doubleValue());
//|b| 對bb開方
double bbb = Math.sqrt(bb.doubleValue());
//使用BigDecimal保證精確計算浮點數
//double aabb = aaa * bbb;
BigDecimal aabb = BigDecimal.valueOf(aaa).multiply(BigDecimal.valueOf(bbb));
//similarity=a.b/|a|*|b|
//divide參數說明:aabb被除數,9表示小數點後保留9位,最後一個表示用標準的四捨五入法
double cos = BigDecimal.valueOf(ab.get()).divide(aabb, 9, BigDecimal.ROUND_HALF_UP).doubleValue();
return cos;
}
/**
* 向每一個Word對象的屬性都注入weight(權重)屬性值
*/
protected static void taggingWeightByFrequency(List<Word> words1, List<Word> words2) {
if (words1.get(0).getWeight() != null && words2.get(0).getWeight() != null) {
return;
}
//詞頻統計(key是詞,value是該詞在這段句子中出現的次數)
Map<String, AtomicInteger> frequency1 = getFrequency(words1);
Map<String, AtomicInteger> frequency2 = getFrequency(words2);
//如果是DEBUG模式輸出詞頻統計信息
// if (LOGGER.isDebugEnabled()) {
// LOGGER.debug("詞頻統計1:\n{}", getWordsFrequencyString(frequency1));
// LOGGER.debug("詞頻統計2:\n{}", getWordsFrequencyString(frequency2));
// }
// 標註權重(該詞出現的次數)
words1.parallelStream().forEach(word -> word.setWeight(frequency1.get(word.getName()).floatValue()));
words2.parallelStream().forEach(word -> word.setWeight(frequency2.get(word.getName()).floatValue()));
}
/**
* 統計詞頻
* @return 詞頻統計圖
*/
private static Map<String, AtomicInteger> getFrequency(List<Word> words) {
Map<String, AtomicInteger> freq = new HashMap<>();
//這步很帥哦
words.forEach(i -> freq.computeIfAbsent(i.getName(), k -> new AtomicInteger()).incrementAndGet());
return freq;
}
/**
* 輸出:詞頻統計信息
*/
private static String getWordsFrequencyString(Map<String, AtomicInteger> frequency) {
StringBuilder str = new StringBuilder();
if (frequency != null && !frequency.isEmpty()) {
AtomicInteger integer = new AtomicInteger();
frequency.entrySet().stream().sorted((a, b) -> b.getValue().get() - a.getValue().get()).forEach(
i -> str.append("\t").append(integer.incrementAndGet()).append("、").append(i.getKey()).append("=")
.append(i.getValue()).append("\n"));
}
str.setLength(str.length() - 1);
return str.toString();
}
/**
* 構造權重快速搜索容器
*/
protected static Map<String, Float> getFastSearchMap(List<Word> words) {
if (CollectionUtils.isEmpty(words)) {
return Collections.emptyMap();
}
Map<String, Float> weightMap = new ConcurrentHashMap<>(words.size());
words.parallelStream().forEach(i -> {
if (i.getWeight() != null) {
weightMap.put(i.getName(), i.getWeight());
} else {
LOGGER.error("no word weight info:" + i.getName());
}
});
return weightMap;
}
}
6、AtomicFloat原子類
package com.e100.hotelcore.stringUtils;
import java.util.concurrent.atomic.AtomicInteger;
public class AtomicFloat extends Number{
private AtomicInteger bits;
public AtomicFloat() {
this(0f);
}
public AtomicFloat(float initialValue) {
bits = new AtomicInteger(Float.floatToIntBits(initialValue));
}
//疊加
public final float addAndGet(float delta) {
float expect;
float update;
do {
expect = get();
update = expect + delta;
} while (!this.compareAndSet(expect, update));
return update;
}
public final float getAndAdd(float delta) {
float expect;
float update;
do {
expect = get();
update = expect + delta;
} while (!this.compareAndSet(expect, update));
return expect;
}
public final float getAndDecrement() {
return getAndAdd(-1);
}
public final float decrementAndGet() {
return addAndGet(-1);
}
public final float getAndIncrement() {
return getAndAdd(1);
}
public final float incrementAndGet() {
return addAndGet(1);
}
public final float getAndSet(float newValue) {
float expect;
do {
expect = get();
} while (!this.compareAndSet(expect, newValue));
return expect;
}
public final boolean compareAndSet(float expect, float update) {
return bits.compareAndSet(Float.floatToIntBits(expect), Float.floatToIntBits(update));
}
public final void set(float newValue) {
bits.set(Float.floatToIntBits(newValue));
}
public final float get() {
return Float.intBitsToFloat(bits.get());
}
@Override
public float floatValue() {
return get();
}
@Override
public double doubleValue() {
return (double) floatValue();
}
@Override
public int intValue() {
return (int) get();
}
@Override
public long longValue() {
return (long) get();
}
@Override
public String toString() {
return Float.toString(get());
}
}
7、總結
把大致思路再捋一下:
(1)先分詞: 分詞當然要按一定規則,不然隨便分那也沒有意義,那這裏通過採用HanLP中文自然語言處理中標準分詞進行分詞。
(2)統計詞頻: 就統計上面詞出現的次數。
(3)通過每一個詞出現的次數,變成一個向量,通過向量公式計算相似率。