/**
* Classifies the tweet into one of three classes (negative, neutral or positive) depending on the
* sentiment value of the tweet and the thresholds specified in the ClassifierOptions
*
* @param tweet String tweet to classify
* @return Sentiment classification (negative, neutral or positive)
*/
public Classification classify(String tweet) {
final double sentimentValue = calculateSentiment(tweet);
return Classification.classifyFromThresholds(
sentimentValue,
ClassifierOptions.getVariable(Variable.CLASSIFICATION_THRESHOLD_LOWER),
ClassifierOptions.getVariable(Variable.CLASSIFICATION_THRESHOLD_HIGHER));
}
private void propagateNegation(List<LexicalToken> lexicalTokens, int index) {
final double negationScopeLength =
ClassifierOptions.getVariable(ClassifierOptions.Variable.NEGATION_SCOPE_LENGTH);
for (int i = index + 1; i <= index + negationScopeLength && i < lexicalTokens.size(); i++) {
lexicalTokens.get(i).setInNegatedContext(true);
if (lexicalTokens.get(i).isAtTheEndOfSentence()) {
break;
}
}
}
public double calculateSentiment(String tweet) {
if (filters != null) {
tweet = filters.apply(tweet);
}
List<LexicalToken> lexicalTokens = LexicalParser.lexicallyParseTweet(tweet, phraseTree);
for (int i = 0; i < lexicalTokens.size(); i++) {
LexicalToken token = lexicalTokens.get(i);
String phrase = token.getPhrase();
if (lexicon.hasToken(phrase)) {
token.setLexicalValue(lexicon.getTokenPolarity(phrase));
} else if (ClassifierOptions.isNegation(phrase)) {
propagateNegation(lexicalTokens, i);
} else if (ClassifierOptions.isIntensifier(phrase)) {
intensifyNext(lexicalTokens, i, ClassifierOptions.getIntensifierValue(phrase));
}
}
return lexicalTokens.stream().mapToDouble(LexicalToken::getSentimentValue).sum();
}