Demo for entrance & exit number for subway stations

Thanks to William’s great help!!! Now I am trying to show the entrance & exit number for subway stations.The numbers of points moving towards / away from the station stands for the number of people passing the Turnstile between 12:00–04:00.

import spatialpixel.mapping.slippymapper as slippymapper
import csv
def setup():
    size(1000, 800, P2D)
global nyc
    nyc = slippymapper.SlippyMapper(40.7541529, -73.9696404, 14, 'carto-darkall', width, height)
with open('entrance01.csv') as f:
        reader = csv.reader(f)
        header = reader.next()
for row in reader:
            traffic000 = float(row[1])
            traffic400 = float(row[2])
            latitude = float(row[8])
            longitude = float(row[9])
            data = {
                'traffic000':traffic000,
                'traffic400':traffic400,
                'latitude':latitude,
                'longitude':longitude,
                }
            nyc.addMarker(latitude, longitude, StationMarker(data))
nyc.render()
def draw():
    background(255)
    nyc.draw()
    #mark.draw()
class StationMarker(slippymapper.DataMarker):
    def __init__(self, data):
        super(StationMarker, self).__init__(data)
        
        self.points = []
def drawMarker(self, x, y, marker):
        
        traffic000 = self.data['traffic000']
        traffic400 = self.data['traffic400']
        
        diam = log(traffic000)
        marker.stroke(255, 0, 0)
        marker.noFill()
        marker.ellipse(x, y, diam, diam)
numPoints = traffic400 - traffic000
        if len(self.points) == 0:
            for i in xrange(numPoints):
                self.points.append(MovingPoint(x, y, -1))
        
        for pt in self.points:
            pt.draw()
        
class MovingPoint(object):
    def __init__(self, x, y, direction=1):
        self.x = x
        self.y = y
        self.theta = random(0, TWO_PI)
        self.radius = int(random(0, 20))
        self.direction = direction
    
    def draw(self):
        stroke(255,0,0)
        x = self.x + ((self.radius + self.direction * frameCount) % 20) * cos(self.theta)
        y = self.y + ((self.radius + self.direction * frameCount) % 20) * sin(self.theta)
        point(x, y)