def CCC(y_true, y_pred):
    """
    Calculate the CCC for two numpy arrays.
    """
    x = y_true
    y = y_pred
    xMean = x.mean()
    yMean = y.mean()
    xyCov = (x * y).mean() - (xMean * yMean)
    xVar = x.var()
    yVar = y.var()
    return 2 * xyCov / (xVar + yVar + (xMean - yMean) ** 2)