to_file.py

#
# Useful function for outputting to structured files without any work - AG
#
def to_file(dest, obj, csv_fields=None, uniq=True, filter_blanks=True, silent=False):
    """
    Dump to a file based on extension
        If .json, do a standard dump() to the file
        If .csv, do a CSV with column headers
        If .lst, do one str/unicode per-line
    """
    try:
        write_stream = open(dest, 'wb')
    except OSError as err:
        print(err)
        raise

    if dest.endswith('.json'):
        # Basic JSON dump
        json_dump(obj, write_stream, sort_keys=False)
    elif dest.endswith('.csv'):
        # Write out a plain CSV file, or one with a header if csv_fields is
        # specified
        if isinstance(obj, (set, tuple, list)) is False:
            raise RuntimeError(
                'ERROR: csv files must be generated from a list/tuple/set')
        from json import dumps
        print(dumps(obj, indent=2))
        if len(obj) and isinstance(obj[0], dict):
            csv_fields = obj[0].keys()
        if csv_fields is not None:
            writer = CSVDictWriter(write_stream, fieldnames=csv_fields)
            writer.writeheader()
        else:
            writer = CSVWriter(write_stream)
        for row in obj:
            if obj is None:
                continue
            if csv_fields is not None:
                if isinstance(row, dict):
                    row = {k.encode('utf-8'): v.encode(
                        'utf-8') for k, v in row.iteritems()}
                    # new_row[k.encode('utf-8')] = v.encode('utf-8')
                    writer.writerow(row)
                elif csv_fields is not None:
                    writer.writerow(dict(zip(csv_fields, row)))
                else:
                    raise RuntimeError('unknown type for row')
            else:
                writer.writerow(row)
    elif dest.endswith('.lst'):
        if isinstance(obj, (set, tuple, list)) is False:
            raise RuntimeError('ERROR: raw/.lst dump object must be set/tuple/list')
        if uniq is True:
            obj = set(obj)
        for row in obj:
            if isinstance(obj, (str, unicode)) is False:
                raise RuntimeError(
                    'ERROR: raw/.lst files must be list of strings')
            if filter_blanks is True and row.strip() == '':
                continue
            write_stream.write(row + '\n')
    else:
        # Unknown extension, assume list of strings
        print('WARN: unknown file extension, dumping as list of strings')
        for row in obj:
            if not isinstance(row, str):
                raise RuntimeError(
                    'ERROR: lst files must be list of strings')
            write_stream.write(row.strip() + '\n')
    write_stream.close()
    if silent is False:
        print('--- Object dumped to file %s ...' % (dest))

This is buggy and not very unicode friendly, don't use it, sorry..