X/cat/lib/similarity.js

function compareTwoStrings(first,second){if((first=first.replace(/\s+/g,""))===(second=second.replace(/\s+/g,"")))return 1;if(first.length<2||second.length<2)return 0;var firstBigrams=new Map;for(let i=0;i<first.length-1;i++){var bigram=first.substring(i,i+2),count=firstBigrams.has(bigram)?firstBigrams.get(bigram)+1:1;firstBigrams.set(bigram,count)}let intersectionSize=0;for(let i=0;i<second.length-1;i++){const bigram=second.substring(i,i+2),count=firstBigrams.has(bigram)?firstBigrams.get(bigram):0;0<count&&(firstBigrams.set(bigram,count-1),intersectionSize++)}return 2*intersectionSize/(first.length+second.length-2)}function findBestMatch(mainString,targetStrings){var ratings=[];let bestMatchIndex=0;for(let i=0;i<targetStrings.length;i++){var currentTargetString=targetStrings[i],currentRating=compareTwoStrings(mainString,currentTargetString);ratings.push({target:currentTargetString,rating:currentRating}),currentRating>ratings[bestMatchIndex].rating&&(bestMatchIndex=i)}return{ratings:ratings,bestMatch:ratings[bestMatchIndex],bestMatchIndex:bestMatchIndex}}function lcs(str1,str2){if(!str1||!str2)return{length:0,sequence:"",offset:0};for(var sequence="",str1Length=str1.length,str2Length=str2.length,num=new Array(str1Length),maxlen=0,lastSubsBegin=0,i=0;i<str1Length;i++){for(var subArray=new Array(str2Length),j=0;j<str2Length;j++)subArray[j]=0;num[i]=subArray}for(var thisSubsBegin=null,i=0;i<str1Length;i++)for(j=0;j<str2Length;j++)str1[i]!==str2[j]?num[i][j]=0:(num[i][j]=0===i||0===j?1:1+num[i-1][j-1],num[i][j]>maxlen&&(maxlen=num[i][j],lastSubsBegin===(thisSubsBegin=i-num[i][j]+1)?sequence+=str1[i]:(lastSubsBegin=thisSubsBegin,sequence="",sequence+=str1.substr(lastSubsBegin,i+1-lastSubsBegin))));return{length:maxlen,sequence:sequence,offset:thisSubsBegin}}function findBestLCS(mainString,targetStrings){var results=[];let bestMatchIndex=0;for(let i=0;i<targetStrings.length;i++){var currentTargetString=targetStrings[i],currentLCS=lcs(mainString,currentTargetString);results.push({target:currentTargetString,lcs:currentLCS}),currentLCS.length>results[bestMatchIndex].lcs.length&&(bestMatchIndex=i)}return{allLCS:results,bestMatch:results[bestMatchIndex],bestMatchIndex:bestMatchIndex}}export{compareTwoStrings,findBestMatch,findBestLCS};