def get(self, col1, col2, method, channel_width, flow_rate=None,
            viscosity=None, add_px_err=False, px_um=None):
        """Get isoelastics

        Parameters
        ----------
        col1: str
            Name of the first feature of all isoelastics
            (e.g. isoel[0][:,0])
        col2: str
            Name of the second feature of all isoelastics
            (e.g. isoel[0][:,1])
        method: str
            The method used to compute the isoelastics
            (must be one of `VALID_METHODS`).
        channel_width: float
            Channel width in µm
        flow_rate: float or `None`
            Flow rate through the channel in µl/s. If set to
            `None`, the flow rate of the imported data will
            be used (only do this if you do not need the
            correct values for elastic moduli).
        viscosity: float or `None`
            Viscosity of the medium in mPa*s. If set to
            `None`, the flow rate of the imported data will
            be used (only do this if you do not need the
            correct values for elastic moduli).
        add_px_err: bool
            If True, add pixelation errors according to
            C. Herold (2017), https://arxiv.org/abs/1704.00572
        px_um: float
            Pixel size [µm], used for pixelation error computation

        See Also
        --------
        dclab.features.emodulus.convert: conversion in-between
            channel sizes and viscosities
        dclab.features.emodulus.corrpix_deform_delta: pixelation
            error that is applied to the deformation data
        """
        if method not in VALID_METHODS:
            validstr = ",".join(VALID_METHODS)
            raise ValueError("`method` must be one of {}!".format(validstr))
        for col in [col1, col2]:
            if col not in dfn.scalar_feature_names:
                raise ValueError("Not a valid feature name: {}".format(col))

        if "isoelastics" not in self._data[method][col2][col1]:
            msg = "No isoelastics matching {}, {}, {}".format(col1, col2,
                                                              method)
            raise KeyError(msg)

        isoel = self._data[method][col1][col2]["isoelastics"]
        meta = self._data[method][col1][col2]["meta"]

        if flow_rate is None:
            flow_rate = meta[1]

        if viscosity is None:
            viscosity = meta[2]

        isoel_ret = self.convert(isoel, col1, col2,
                                 channel_width_in=meta[0],
                                 channel_width_out=channel_width,
                                 flow_rate_in=meta[1],
                                 flow_rate_out=flow_rate,
                                 viscosity_in=meta[2],
                                 viscosity_out=viscosity,
                                 inplace=False)

        if add_px_err:
            self.add_px_err(isoel=isoel_ret,
                            col1=col1,
                            col2=col2,
                            px_um=px_um,
                            inplace=True)

        return isoel_ret
Get isoelastics

        Parameters
        ----------
        col1: str
            Name of the first feature of all isoelastics
            (e.g. isoel[0][:,0])
        col2: str
            Name of the second feature of all isoelastics
            (e.g. isoel[0][:,1])
        method: str
            The method used to compute the isoelastics
            (must be one of `VALID_METHODS`).
        channel_width: float
            Channel width in µm
        flow_rate: float or `None`
            Flow rate through the channel in µl/s. If set to
            `None`, the flow rate of the imported data will
            be used (only do this if you do not need the
            correct values for elastic moduli).
        viscosity: float or `None`
            Viscosity of the medium in mPa*s. If set to
            `None`, the flow rate of the imported data will
            be used (only do this if you do not need the
            correct values for elastic moduli).
        add_px_err: bool
            If True, add pixelation errors according to
            C. Herold (2017), https://arxiv.org/abs/1704.00572
        px_um: float
            Pixel size [µm], used for pixelation error computation

        See Also
        --------
        dclab.features.emodulus.convert: conversion in-between
            channel sizes and viscosities
        dclab.features.emodulus.corrpix_deform_delta: pixelation
            error that is applied to the deformation data