Draws the precision-recall curves computed in score on the axes.

def draw(self):
        """
        Draws the precision-recall curves computed in score on the axes.
        """
        if self.iso_f1_curves:
            for f1 in self.iso_f1_values:
                x = np.linspace(0.01, 1)
                y = f1 * x / (2 * x - f1)
                self.ax.plot(x[y>=0], y[y>=0], color='#333333', alpha=0.2)
                self.ax.annotate('$f_1={:0.1f}$'.format(f1), xy=(0.9, y[45]+0.02))

        if self.target_type_ == BINARY:
            return self._draw_binary()
        return self._draw_multiclass()