fruit_counter.py

from socketIO_client import SocketIO
import json

SOCKET_HOST = 'https://brand.nioinstances.com'

class RunningAverage:
	"""
	Keeps a running average of some grocery type (eg, fruit)
	"""
	def __init__(self):
		self.cart_count = 0
		self.fruit_average = 0
		print "initialized a new running average counter"

	def add_cart(self, message, *args):
		# create a cart, and count its total number of fruits
		cart_fruits = Cart(message).getByType('fruit')
		self.cart_count += 1

		# update running total of fruits
		self.fruit_average = (1./self.cart_count)*((self.fruit_average * (self.cart_count-1))+cart_fruits)
		print "current fruit average: ", self.fruit_average

class Cart:
	"""A cart that knows how to count its own objects"""
	def __init__(self, message):
		self.json = json.loads(message)

	def getByType(self, type):
		# count all of the given type in the cart
		subtotal = 0
		for item in self.json['cart']:
			if item['type']==type:
				subtotal += item['quantity']
		return subtotal

ra = RunningAverage()

with SocketIO(SOCKET_HOST) as sock:
    # Set up our message handler
    sock.on('recvData', ra.add_cart)
    # Join the "fruits" room
    sock.emit('ready', 'groceries')
    # Wait for messages to come through! Ctrl-C to quit
    sock.wait()