topic.py

class Topic(object):
    """
    Topic
    
    @type _id: int
    @param _id: the id of the topic
    
    @type _x: float
    @param _x: the x coordinate in the plane
    
    @type _y: float
    @param _y: the y coordinate in the plane
    
    @type _current_distance: float
    @param _current_distance: the current distance from the origin(origin being the query coordiantaes) 
    
    @type _qn: int
    @param _qn: the number of questions associated with this topics
    
    @type _questions: list
    @param _questions: the list of the questions associated with this topic
    """
    
    def __init__(self, id, x, y):
        self._id = id
        self._x = x
        self._y = y
        self._current_distance = 0        
        self._qn = 0
        self._questions = []
    
    def __gt__(self, topic):
        delta = self._current_distance - topic._current_distance
        if delta < -THRESHOLD:
            return True
        if delta > THRESHOLD:
            return False
        return True if self._id > topic._id else False 

    def add(self, question):
        self._qn += 1
        self._questions.append(question)
        
    def get_questions(self, qn, questions):       
        go_on = True 
        for question in self._questions:
            if question not in questions:
                questions.append(question)
                qn -= 1                    
                if qn == 0:
                    go_on = False
                    break
        return sorted(questions, reverse=True), qn, go_on        
    
    def set_current_distance(self, origin_x, origin_y):
        self._current_distance = self.euclidean_dis(self._x, self._y, origin_x, origin_y)        
    
    @staticmethod
    def euclidean_dis(x1, y1, x2, y2):
        return math.sqrt(pow(x1 - x2, 2) + pow(y1 - y2, 2))