def parse_log_file(filename, begin_item_index=0):
    """log_file format   \tkey: value\t key:value\t key:value\t ... """
    ret = {}
    with open(filename, 'r') as fin:
        for line in fin.readlines():
            items = line.split('\t')

            if len(items) < 1:  # ignore error
                continue

            for item in items[begin_item_index:]:
                key, value = parse_pair(item)
                if key not in ret:
                    ret[key] = []
                ret[key].append(value)

    return ret
log_file format   	key: value	 key:value	 key:value	 ... 
scripts/plot_many.py