def secure_filename(filename):
    r"""Borrowed from :mod:`werkzeug.utils`, under the BSD 3-clause license.

    Pass it a filename and it will return a secure version of it.  This
    filename can then safely be stored on a regular file system and passed
    to :func:`os.path.join`.  The filename returned is an ASCII only string
    for maximum portability.

    On windows systems the function also makes sure that the file is not
    named after one of the special device files.

    >>> secure_filename("My cool movie.mov")
    'My_cool_movie.mov'
    >>> secure_filename("../../../etc/passwd")
    'etc_passwd'
    >>> secure_filename(u'i contain cool \xfcml\xe4uts.txt')
    'i_contain_cool_umlauts.txt'

    The function might return an empty filename.  It's your responsibility
    to ensure that the filename is unique and that you generate random
    filename if the function returned an empty one.

    :param filename: the filename to secure
    """
    _filename_ascii_strip_re = re.compile(r'[^A-Za-z0-9_.-]')
    _windows_device_files = ('CON', 'AUX', 'COM1', 'COM2', 'COM3', 'COM4',
                             'LPT1', 'LPT2', 'LPT3', 'PRN', 'NUL')
    if isinstance(filename, text_type):
        from unicodedata import normalize
        filename = normalize('NFKD', filename).encode('ascii', 'ignore')
        if not PY2:
            filename = filename.decode('ascii')
    for sep in os.path.sep, os.path.altsep:
        if sep:
            filename = filename.replace(sep, ' ')
    filename = str(_filename_ascii_strip_re.sub('', '_'.join(
                   filename.split()))).strip('._')

    # on nt a couple of special files are present in each folder.  We
    # have to ensure that the target file is not such a filename.  In
    # this case we prepend an underline
    if os.name == 'nt' and filename and \
       filename.split('.')[0].upper() in _windows_device_files:
        filename = '_' + filename

    return filename
def init(cls, eltype, data, kdims, vdims):
        import cudf
        import pandas as pd

        element_params = eltype.param.objects()
        kdim_param = element_params['kdims']
        vdim_param = element_params['vdims']

        if isinstance(data, (cudf.Series, pd.Series)):
            data = data.to_frame()

        if not isinstance(data, cudf.DataFrame):
            data, _, _ = PandasInterface.init(eltype, data, kdims, vdims)
            data = cudf.from_pandas(data)

        columns = list(data.columns)
        ncols = len(columns)
        index_names = [data.index.name]
        if index_names == [None]:
            index_names = ['index']
        if eltype._auto_indexable_1d and ncols == 1 and kdims is None:
            kdims = list(index_names)

        if isinstance(kdim_param.bounds[1], int):
            ndim = min([kdim_param.bounds[1], len(kdim_param.default)])
        else:
            ndim = None
        nvdim = vdim_param.bounds[1] if isinstance(vdim_param.bounds[1], int) else None
        if kdims and vdims is None:
            vdims = [c for c in columns if c not in kdims]
        elif vdims and kdims is None:
            kdims = [c for c in columns if c not in vdims][:ndim]
        elif kdims is None:
            kdims = list(columns[:ndim])
            if vdims is None:
                vdims = [d for d in columns[ndim:((ndim+nvdim) if nvdim else None)]
                         if d not in kdims]
        elif kdims == [] and vdims is None:
            vdims = list(columns[:nvdim if nvdim else None])

        # Handle reset of index if kdims reference index by name
        for kd in kdims:
            kd = dimension_name(kd)
            if kd in columns:
                continue
            if any(kd == ('index' if name is None else name)
                   for name in index_names):
                data = data.reset_index()
                break
        if any(isinstance(d, (np.int64, int)) for d in kdims+vdims):
            raise DataError("cudf DataFrame column names used as dimensions "
                            "must be strings not integers.", cls)

        if kdims:
            kdim = dimension_name(kdims[0])
            if eltype._auto_indexable_1d and ncols == 1 and kdim not in columns:
                data = data.copy()
                data.insert(0, kdim, np.arange(len(data)))

        for d in kdims+vdims:
            d = dimension_name(d)
            if len([c for c in columns if c == d]) > 1:
                raise DataError('Dimensions may not reference duplicated DataFrame '
                                'columns (found duplicate %r columns). If you want to plot '
                                'a column against itself simply declare two dimensions '
                                'with the same name. '% d, cls)
        return data, {'kdims':kdims, 'vdims':vdims}, {}