filters.py 文件源码

def get_filter(name_or_function, **kwargs):
    '''Retrieve a window given its name or function handle.

    Parameters
    ----------
    name_or_function : str or callable
        If a function, returns `name_or_function(**kwargs)`.

        If a string, and it matches the name of one of the defined
        filter functions, the corresponding function is called with `**kwargs`.

        If a string, and it matches the name of a pre-computed filter,
        the corresponding filter is retrieved, and kwargs is ignored.

        Valid pre-computed filter names are:
            - 'kaiser_fast'
            - 'kaiser_best'

    Returns
    -------
    half_window : np.ndarray
        The right wing of the interpolation filter

    precision : int > 0
        The number of samples between zero-crossings of the filter

    rolloff : float > 0
        The roll-off frequency of the filter as a fraction of Nyquist

    Raises
    ------
    NotImplementedError
        If `name_or_function` cannot be found as a filter.
    '''
    if name_or_function in FILTER_FUNCTIONS:
        return getattr(sys.modules[__name__], name_or_function)(**kwargs)
    elif six.callable(name_or_function):
        return name_or_function(**kwargs)
    else:
        try:
            return load_filter(name_or_function)
        except (IOError, ValueError):
            raise NotImplementedError('Cannot load filter definition for '
                                      '{}'.format(name_or_function))