Levenshtein Distance Algorithm (R code)

Levenshtein Distance represents the minimum number of letter changes required to convert a word to another word.

The below R language code gives the Levenshtein Distance (letter changes required) to convert "Saturday" to "Sunday".

str1 <- c("Saturday")

str2 <- c("Sunday")

str1knt <- nchar(str1)

str2knt <- nchar(str2)

str11<-substring(str1,1:str1knt,1:str1knt)

m2<-matrix(c(" ","",str11),nrow=1,ncol=str1knt+2,byrow=FALSE)

sq<-seq(0,str1knt)

m2<-rbind(m2,c(" ",sq))

i=1

k=str2knt

while(k>0){ 

m2=rbind(m2,c(substring(str2,i,i),i,replicate(str1knt,0)))

k=k-1

i=i+1

}

k=3

while(k<=str2knt+2){

i=3

                while(i<=str1knt+2){

                apex<-as.numeric(m2[k-1,i-1])

                horiz<-as.numeric(m2[k-1,i])

                verti<-as.numeric(m2[k,i-1])

                s2char<-m2[k,1]

                s1char<-m2[1,i]

                if(s2char==s1char){ m2[k,i] <- min(apex,horiz,verti)} else { m2[k,i] <- min(apex,horiz,verti)+1}

                i=i+1

                }

k=k+1

}

LevenshteinDistance <- as.numeric(m2[k-1,i-1])

LevenshteinDistance