split up track hubs into chunks so UCSC doesn't get mad

split_track_hubs.py

def single_track(track):
    within_track = False
    lines = []
    with open(track) as f:
        for line in f:
#             print line,
            if line.startswith('track') and within_track:
                within_track =  False
                yield lines
                lines = [line]
            else:
                lines.append(line)
                within_track = True
                
MAX_FILE_SIZE = 262144

all_written = False

n = 0

single_tracks = single_track('trackDb.txt')

while not all_written:
    filename = 'trackDb_{}.txt'.format(n)
    with open(filename, 'w') as f:
        while os.stat(filename).st_size < MAX_FILE_SIZE:
            try:
                f.writelines(single_tracks.next())
            except StopIteration:
                all_written = True
                break
    n += 1