Show the number of online viewers of ETV on a 7-segment display. For Raspberry Pi and Adafruit LED Backpack

err.py

#!/usr/bin/python

# Show the number of viewers of ERR ETV online TV-channel on a 7-segment LCD
# Built for the Raspberry Pi
# 
# http://otse.err.ee/etv/
# https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/blob/master/Adafruit_LEDBackpack/Adafruit_7Segment.py
# https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/blob/master/Adafruit_LEDBackpack/Adafruit_LEDBackpack.py
# https://github.com/adafruit/Adafruit-Raspberry-Pi-Python-Code/blob/master/Adafruit_I2C/Adafruit_I2C.py
# 
# Author Ando Roots <ando@sqroot.eu> 2013

import time, urllib2
from Adafruit_7Segment import SevenSegment
import RPi.GPIO as GPIO

class ERROnline:
	
	# Refresh interval in seconds
	CHECK_INTERVAL = 10
	
	# ERR internal API endpoint, gives JS output
	API_URL = 'http://otse.err.ee/xml/live-etv.html'
	
	# 7-segment display (run i2cdetect -y 1 to get the addr)
	segment = SevenSegment(address=0x70)
	
	# Write a 4-digit number to the LCD
	def write_number(self, value):
		value = int(value)
		if value > 9999:
			print "Value %s is out of bounds, setting to 9999" % value
			value = 9999
		value = str(value).zfill(4)
		self.segment.writeDigit(0, int(value[0]))
		self.segment.writeDigit(1, int(value[1]))
		self.segment.writeDigit(3, int(value[2]))
		self.segment.writeDigit(4, int(value[3]))
		return self
	
	# Does an HTTP API query and returns the number of online viewers
	def get_online_count(self):
		js_response = urllib2.urlopen(self.API_URL).read()
		parts = js_response.split("$('#viewers').html('")
		return parts[1].split("');")[0]
	
	# Main loop
	def run(self):
		print "Running the program - press Ctrl + C to exit."
		time.sleep(2)
		
		previous_count = 0
		while True:
			self.segment.setColon(1)
			
			online_count = self.get_online_count()
			
			# Change LCD / stdout 
			if online_count != previous_count:
				check_time = time.strftime("%Y-%m-%d %H:%M:%S", time.gmtime())
				print "[%s] ETV Online: %s people watching." % (check_time, online_count)
				self.write_number(online_count)
				previous_count = online_count
				
			self.segment.setColon(0)
			time.sleep(self.CHECK_INTERVAL)
		    
    # Cleanup on exit
	def __del__(self):
		self.segment.disp.clear()
		
# Run the program
monitor = ERROnline().run()