baglaser2json.py

from glob import glob
import rosbag
import yaml
import json
import os
fnames = glob('/folder/*.bag')

print fnames

bags = [rosbag.Bag(f) for f in fnames]

for fname, bag in zip(fnames, bags):
    print "processing {}".format(fname)
    for topic, msg, t in bag.read_messages("/scan"):
        with open(os.path.splitext(fname)[0] + ".json", 'w') as ff:
            ff.write(json.dumps(yaml.load(str(msg))))
        break