private int GetTotalAnsweringFrequency(AnswerStatistic answerStatistic, AnsweredQuestion answeredQuestion)
{
if (!answerStatistic.AnsweredQuestionsById.ContainsKey(answeredQuestion.QuestionId))
return answeringChoicesCount;
return answerStatistic.AnsweredQuestionsById[answeredQuestion.QuestionId].ChoicesFrequenciesTotal;
}
public string GetNextQuestionId(IList<AnsweredQuestion> answeredQuestions, IList<AnswerGuess> answerGuesses)
{
string nextQuestionId = null;
double minQuestionEntropy = double.MaxValue;
var answeredQuestionIds = new HashSet<string>(answeredQuestions.Select(q => q.QuestionId));
foreach (var questionId in questionStatistics.Keys)
{
if (answeredQuestionIds.Contains(questionId))
continue;
double entropy = 0.0;
for (int i = 0; i < answeringChoicesCount; i++)
{
var answeredQuestion = new AnsweredQuestion { Choise = i, QuestionId = questionId };
var probabilities = answerGuesses.Select(ag => ag.Probability *
GetAnsweringFrequency(ag.AnswerStatistic,answeredQuestion) /
GetTotalAnsweringFrequency(ag.AnswerStatistic, answeredQuestion))
.ToList();
var totalProbability = probabilities.Sum();
var answeredQuestionProbability = (double)questionStatistics[questionId].ChoicesFrequencies[i] /
questionStatistics[questionId].ChoicesFrequenciesTotal;
foreach (var probability in probabilities)
{
double correctedProbability = probability / totalProbability;
entropy += -correctedProbability * Math.Log(correctedProbability, 2.0) * answeredQuestionProbability;
}
}
if (entropy < minQuestionEntropy)
{
minQuestionEntropy = entropy;
nextQuestionId = questionId;
}
}
return nextQuestionId;
}
private int GetAnsweringFrequency(AnswerStatistic answerStatistic, AnsweredQuestion answeredQuestion)
{
if (!answerStatistic.AnsweredQuestionsById.ContainsKey(answeredQuestion.QuestionId))
return 1;
return answerStatistic.AnsweredQuestionsById[answeredQuestion.QuestionId].ChoicesFrequencies[answeredQuestion.Choise];
}