DataScienceCapstoneProject/model.R at master · nihathalici/DataScienceCapstoneProject · GitHub

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library(tm)

bigram <- readRDS(file="data/final_bigram_sm.Rda")
trigram <- readRDS(file="data/final_trigram_sm.Rda")
fourgram <- readRDS(file="data/final_fourgram_sm.Rda")


nextWordPredictor <- function(inputTxt) {

  if(nchar(inputTxt) > 0) {
    #clean input
    inputTxt <- tolower(inputTxt)
    inputTxt <- removeNumbers(inputTxt)
    inputTxt <- removePunctuation(inputTxt)
    inputTxt <- stripWhitespace(inputTxt)

    #split into words
    inputList <- unlist(strsplit(inputTxt, " "))

    print(inputList)


    numWords <- length(inputList)

    print(numWords)

    runBigram <- function(words){
      bigram[bigram$terms$one == words,]$terms$two
    }

    runTrigram <- function(words){
      trigram[trigram$terms$one == words[1] &
                trigram$terms$two == words[2],]$terms$three
    }

    runFourgram <- function(words) {
      fourgram[ fourgram$terms$one == words[1] &
                  fourgram$terms$two == words[2] &
                  fourgram$terms$three == words[3],]$terms$four
    }

    if(numWords == 1) {
      #print("running bigram")
      predList <- runBigram(inputList[1])
    }else if (numWords == 2) {
      #print("running trigram")
      word1 <- inputList[1]
      word2 <- inputList[2]
      predList <- runTrigram(c(word1, word2))

      if(length(predList) == 0){
        #print("Trigram failed running bigram")
        predList <- runBigram(word2)
      }
    }else {
      #print("running fourgram")
      word1 <- inputList[numWords-2]
      word2 <- inputList[numWords-1]
      word3 <- inputList[numWords]
      predList <- runFourgram(c(word1, word2, word3))

      if(length(predList) == 0){
        #print("fourgram failed running trigram")
        predList <- runTrigram(c(word2,word3))
      }

      if(length(predList) == 0){
        #print("trigram failed running bigram")
        predList <- runBigram(word3)
      }
    }

    #Return top n predictors
    n <- 4
    tp <- length(predList)

    if( tp >= n){
      predList <- predList[1:n]
    }

    as.character(predList)
  }else{
    ""
  }


}
# ptm <- proc.time()
# nextWordPredictor("the world")
# proc.time() - ptm