def evaluate_raw(self, y, y_hat, **kwargs):
        y_bar = np.nanmean(y)
        ss_residual = np.nansum( (y - y_hat)**2 )
        ss_total = np.nansum( (y - y_bar)**2 )
        r_squared = 1 - ss_residual / ss_total

        return {"r_squared": r_squared}
Return the directory for the chart configuration files (used by the
dataset/ETHPy150Open impactlab/eemeter/eemeter/meter/fitness.py/RSquared.evaluate_raw--crossover with--dataset/ETHPy150Open UDST/urbansim/urbansim/utils/misc.py/charts_dir