Fetch and untile tiled Himawari-8 images from the http://himawari8.nict.go.jp PNG endpoint, then set them as desktop background on OSX

himawari.py

import requests
import sys
from datetime import datetime, timedelta
import pytz
from PIL import Image
from StringIO import StringIO
import os
import logging

# python himawari.py
# stolen from https://gist.github.com/celoyd/39c53f824daef7d363db

# Fetch Himawari-8 full disks at a given zoom level and set as desktop.
# Valid zoom levels seem to be powers of 2, 1..16, and 20.
#
# To do:
# - Better errors (e.g., catch the "No Image" image).
# - Librarify.


# Tile size for this dataset:
width = 550
height = 550


# time = parse(sys.argv[1])
tz = pytz.timezone('UTC')
time = datetime.now(tz) - timedelta(minutes=40)

scale = 8
out = sys.argv[1]


base = 'http://himawari8.nict.go.jp/img/D531106/%sd/550' % (scale)

tiles = [[None] * scale] * scale

def pathfor(t, x, y):
    return "%s/%s/%02d/%02d/%02d%02d00_%s_%s.png" \
    % (base, t.year, t.month, t.day, t.hour, (t.minute / 10) * 10, x, y)


sess = requests.Session() # so requests will reuse the connection
png = Image.new('RGB', (width*scale, height*scale))

def fetch_and_set():
    for x in range(scale):
        for y in range(scale):
            path = pathfor(time, x, y)
            tiledata = sess.get(path).content
            tile = Image.open(StringIO(tiledata))
            png.paste(tile, (width*x, height*y, width*(x+1), height*(y+1)))

    png.save(out, 'PNG')

    os.system("osascript -e 'tell application \"Finder\" to set desktop picture to POSIX file \"" + out + "\"'")
    os.system("killall Dock")

try:
    fetch_and_set()
except requests.exceptions.ConnectionError:
    logging.exception('')
    try:
        fetch_and_set()
    except requests.exceptions.ConnectionError:
        logging.exception('')