BoM radar gif

main.py

#!/usr/bin/env python
# MIT Licence
# Gets radar overlays from the Australian Bureau of Meteorology radar pages
# and creates an animated gif out of it.

# Needs requests and pillow (the python packages) and ImageMagick the standalone graphics
# program to be installed and available to work.

# All radar images are copyright BoM, and this script should not be used for 
# commercial purposes, or possibly at all.

# Change this url variable to the radar you would like to convert to gif.
radar_url = "http://www.bom.gov.au/products/IDR023.loop.shtml#skip"

import requests, re, os, subprocess
from PIL import Image
from StringIO import StringIO

# create a new directory to store our data in
directory_prefix = 'radar_images'
directory_index = 0
directory_name = None
while True:
    directory_name = directory_prefix + str(directory_index)
    if os.path.exists(directory_name):
        directory_index += 1
    else:
        os.mkdir(directory_name)
        break

# the png images that make up the radar animation are stored in a js variable
# on the BoM radar page called theImageNames
IMAGE_URL_REGEX = re.compile(r'theImageNames\[\d\]\s+=\s+"(.*)"')
# get the radar page html
r = requests.get(radar_url)
    
# fetch the image data and save it
images = []
for image_url in IMAGE_URL_REGEX.findall(r.text):
    img_bytes = requests.get(image_url).content
    i = Image.open(StringIO(img_bytes))
    i.save(os.path.join(directory_name, image_url[-20:]))

# use ImageMagick to turn the pngs into gif
subprocess_command = ['convert']
convert_options = ['-background',
                   'white', 
                   '-alpha',
                   'remove',
                   '-layers',
                   'OptimizePlus',
                   '-delay',
                   '25x100',
                   directory_name+ '/*.png',
                   '-loop',
                   '0',
                   directory_name + '/radar.gif']
subprocess_command.extend(convert_options)
# call ImageMagicks convert function to generate a gif from the downloaded pngs
subprocess.call(' '.join(subprocess_command), shell=True)