No code exits to deal with the parameter *fact* for matplotlib 2.1.0 as shown below.

@docstring.dedent_interpd
def set_thetagrids(self, angles, labels=None, frac=None, fmt=None,
                   **kwargs):
    """
    Set the angles at which to place the theta grids (these
    gridlines are equal along the theta dimension).  *angles* is in
    degrees.

    *labels*, if not None, is a ``len(angles)`` list of strings of
    the labels to use at each angle.

    If *labels* is None, the labels will be ``fmt %% angle``

    *frac* is the fraction of the polar axes radius at which to
    place the label (1 is the edge). e.g., 1.05 is outside the axes
    and 0.95 is inside the axes.

    Return value is a list of tuples (*line*, *label*), where
    *line* is :class:`~matplotlib.lines.Line2D` instances and the
    *label* is :class:`~matplotlib.text.Text` instances.

    kwargs are optional text properties for the labels:

    %(Text)s

    ACCEPTS: sequence of floats
    """
    # Make sure we take into account unitized data
    angles = self.convert_yunits(angles)
    angles = np.asarray(angles, float)
    self.set_xticks(angles * (np.pi / 180.0))
    if labels is not None:
        self.set_xticklabels(labels)
    elif fmt is not None:
        self.xaxis.set_major_formatter(mticker.FormatStrFormatter(fmt))
    for t in self.xaxis.get_ticklabels():
        t.update(kwargs)
    return self.xaxis.get_ticklines(), self.xaxis.get_ticklabels()