tfIdfProbability function

List<Map<String, double>> tfIdfProbability (
  1. TokenizationOutput tokenOut
)

Word probability calculation - Term Frequency - Inverse Document Frequency.

This function is used to calculate the probability of a word to be the main topic (important score)

Returns probability for each word in each document

Implementation

List<Map<String, double>> tfIdfProbability(TokenizationOutput tokenOut) {
  List<Map<String, double>> documentExclusiveWP = [];
  int documentCount = tokenOut.documentTotalWord.length;

  //calculate the IDF first, the value is used for all document
  Map<String, double> wordIDF = {};
  tokenOut.wordInDocumentOccurrence.forEach((key, val) {
    wordIDF[key] = log(documentCount / tokenOut.wordInDocumentOccurrence[key]) /
        ln10; //log10
  });

  //for all document
  for (int i = 0; i < tokenOut.documentTotalWord.length; i++) {
    Map<String, double> currentWordProb = {};
    //for all word available in a document
    tokenOut.documentBOW[i].forEach((key, val) {
      var tf = val / tokenOut.documentTotalWord[i];
      var idf = wordIDF[key];
      currentWordProb[key] = tf * idf;
    });
    //every document have their own word probability
    documentExclusiveWP.add(currentWordProb);
  }

  return documentExclusiveWP;
}