\
        :returns: the ratio part of the dominant label for each unit.
        :rtype: 2D :class:`numpy.ndarray`

def get_precision(self):
        """\
        :returns: the ratio part of the dominant label for each unit.
        :rtype: 2D :class:`numpy.ndarray`
        """
        assert self.classifier is not None, 'not calibrated'
        arr = np.zeros((self._som.nrows, self._som.ncols))
        for ij, (lbl, p) in self.classifier.items():
            arr[ij] = p
        return arr