gistfile1.py

def test_map_reduce_finalize(self):
    """Ensure finalize is running by simulating "hotness" 
    ranking with Reddit algorithm.
    """
    from time import mktime

    class Link(Document):
        title = StringField()
        up_votes = IntField()
        down_votes = IntField()
        submitted = DateTimeField()

    Link.drop_collection()

    now = datetime.utcnow()

    # Note: Test data taken from a custom Reddit homepage on
    # Fri, 12 Feb 2010 14:36:00 -0600. Link ordering should 
    # reflect order of insertion below.

    Link(title = "Google Buzz auto-followed a woman's abusive ex ...", 
         up_votes = 1079,
         down_votes = 553,
         submitted = now-timedelta(hours=4)).save()
    Link(title = "We did it! Barbie is a computer engineer.",
         up_votes = 481,
         down_votes = 124,
         submitted = now-timedelta(hours=2)).save()
    Link(title = "This Is A Mosquito Getting Killed By A Laser", 
         up_votes = 1446,
         down_votes = 530,
         submitted=now-timedelta(hours=13)).save()
    Link(title = "Arabic flashcards land physics student in jail.",
         up_votes = 215, 
         down_votes = 105,
         submitted = now-timedelta(hours=6)).save()
    Link(title = "The Burger Lab: Presenting, the Flood Burger",
         up_votes = 48,
         down_votes = 17,
         submitted = now-timedelta(hours=5)).save()
    Link(title="How to see polarization with the naked eye",
         up_votes = 74,
         down_votes = 13,
         submitted = now-timedelta(hours=10)).save()

    map_f = """
        function() {
            emit(this._id, {up_delta: this.up_votes - this.down_votes,
                            reddit_epoch: new Date(2005, 12, 8, 7, 46, 43, 0).getTime(),
                            sub_date: this.submitted.getTime()})
        }
    """

    reduce_f = """
        function(key, values) {
            data = values[0];
                        
            x = data.up_delta;
        
            // calculate time diff between reddit epoch and submission
            sec_since_epoch = data.sub_date - data.reddit_epoch;
            sec_since_epoch /= 1000;
        
            // calculate 'Y'
            if(x > 0) {
                y = 1;
            } else if (x = 0) {
                y = 0;
            } else {
                y = -1;
            }
        
            // calculate 'Z', the maximal value
            if(Math.abs(x) >= 1) {
                z = Math.abs(x);
            } else {
                z = 1;
            }
        
            return {x: x, y: y, z: z, t_s: sec_since_epoch};
        }
    """

    finalize_f = """
        function(key, value) {
            // f(sec_since_epoch,y,z) = log10(z) + ((y*sec_since_epoch) / 45000)
            z_10 = Math.log(value.z) / Math.log(10);
            weight = z_10 + ((value.y * value.t_s) / 45000);
            return weight;
        }
    """

    # ensure both artists are found
    results = Link.objects.order_by("-value")
    results = results.map_reduce(map_f, reduce_f, finalize_f=finalize_f)
    results = list(results)

    # do something interesting with results

    Link.drop_collection()