Called from the fit method, this method creates a scatter plot that
        draws each instance as a class or target colored point, whose location
        is determined by the feature data set.

        If y is not None, then it draws a scatter plot where each class is in a
        different color.

def draw(self, X, y, **kwargs):
        """Called from the fit method, this method creates a scatter plot that
        draws each instance as a class or target colored point, whose location
        is determined by the feature data set.

        If y is not None, then it draws a scatter plot where each class is in a
        different color.
        """
        nan_locs = self.get_nan_locs()
        if y is None:
            x_, y_ = list(zip(*nan_locs))
            self.ax.scatter(x_, y_, alpha=self.alpha, marker=self.marker, label=None)
        else:
            self.draw_multi_dispersion_chart(nan_locs)