read temperature from dht22 for raspberry pi

dht22.py

#!/usr/bin/python
import sys
import time
import Adafruit_DHT

sensor = Adafruit_DHT.DHT22
pin = 4

while True:
  humidity, temperature = Adafruit_DHT.read_retry(sensor, pin)
  if humidity is not None and temperature is not None:
	print 'Temp={0:0.1f}*C  Humidity={1:0.1f}%'.format(temperature, humidity)
	time.sleep(2)
  else:
	print 'Failed to get reading. Try again!'