Method apply_function

mne/io/base.py:1062–1151

Apply a function to a subset of channels. %(applyfun_summary_raw)s Parameters ---------- %(fun_applyfun)s %(picks_all_data_noref)s %(dtype_applyfun)s %(n_jobs)s Ignored if ``channel_wise=False`` as the workload is split across cha

(
        self,
        fun,
        picks=None,
        dtype=None,
        n_jobs=None,
        channel_wise=True,
        verbose=None,
        **kwargs,
    )

    @verbose
    def apply_function(
        self,
        fun,
        picks=None,
        dtype=None,
        n_jobs=None,
        channel_wise=True,
        verbose=None,
        **kwargs,
    ):
        """Apply a function to a subset of channels.

        %(applyfun_summary_raw)s

        Parameters
        ----------
        %(fun_applyfun)s
        %(picks_all_data_noref)s
        %(dtype_applyfun)s
        %(n_jobs)s Ignored if ``channel_wise=False`` as the workload
            is split across channels.
        %(channel_wise_applyfun)s

            .. versionadded:: 0.18
        %(verbose)s
        %(kwargs_fun)s

        Returns
        -------
        self : instance of Raw
            The raw object with transformed data.
        """
        _check_preload(self, "raw.apply_function")
        picks = _picks_to_idx(self.info, picks, exclude=(), with_ref_meg=False)

        if not callable(fun):
            raise ValueError("fun needs to be a function")

        data_in = self._data
        if dtype is not None and dtype != self._data.dtype:
            self._data = self._data.astype(dtype)

        args = getfullargspec(fun).args + getfullargspec(fun).kwonlyargs
        if channel_wise is False:
            if ("ch_idx" in args) or ("ch_name" in args):
                raise ValueError(
                    "apply_function cannot access ch_idx or ch_name "
                    "when channel_wise=False"
                )
        if "ch_idx" in args:
            logger.info("apply_function requested to access ch_idx")
        if "ch_name" in args:
            logger.info("apply_function requested to access ch_name")

        if channel_wise:
            parallel, p_fun, n_jobs = parallel_func(_check_fun, n_jobs)
            if n_jobs == 1:
                # modify data inplace to save memory