Write ARFF file

    Parameters
    ----------
    data : :class:`pandas.DataFrame`
        DataFrame containing data

    filename : string or file-like object
        Path to ARFF file or file-like object. In the latter case,
        the handle is closed by calling this function.

    relation_name : string, optional, default: "pandas"
        Name of relation in ARFF file.

    index : boolean, optional, default: True
        Write row names (index)

def writearff(data, filename, relation_name=None, index=True):
    """Write ARFF file

    Parameters
    ----------
    data : :class:`pandas.DataFrame`
        DataFrame containing data

    filename : string or file-like object
        Path to ARFF file or file-like object. In the latter case,
        the handle is closed by calling this function.

    relation_name : string, optional, default: "pandas"
        Name of relation in ARFF file.

    index : boolean, optional, default: True
        Write row names (index)
    """
    if isinstance(filename, str):
        fp = open(filename, 'w')

        if relation_name is None:
            relation_name = os.path.basename(filename)
    else:
        fp = filename

        if relation_name is None:
            relation_name = "pandas"

    try:
        data = _write_header(data, fp, relation_name, index)
        fp.write("\n")
        _write_data(data, fp)
    finally:
        fp.close()