levenshtein-distance-r

#Takes two character vectors
lev_dist_better <- function(s, t){
  if(identical(s, t)) return(0)
  if(length(s) == 0) return(length(t))
  if(length(t) == 0) return(length(s))
  
  #initialise v0 with a sequence from 0 to length of t + 1
  previous <- seq(1, length(t) + 1, 1)
  current <- c(rep(0, length(t) + 1))

  
  for(i in 1:length(s)){
    current[1] <- i +1
    
    
    for(j in 1:length(t)){
      cost <- ifelse(s[i] == t[j], 0, 1)
      current[j + 1] = min(current[j] + 1, previous[j+1] + 1, previous[j] + cost)
    }
    
    for(j in 1:length(previous))
      previous[j] = current[j]
    
    
  }
  return(current[length(t)+1]-1)
}