transform.py 文件源码

def _yj_trans_single_x(x, lam):
    if x >= 0:
        # Case 1: x >= 0 and lambda is not 0
        if not _eqls(lam, ZERO):
            return (np.power(x + 1, lam) - 1.0) / lam

        # Case 2: x >= 0 and lambda is zero
        return log(x + 1)
    else:
        # Case 2: x < 0 and lambda is not two
        if not lam == 2.0:
            denom = 2.0 - lam
            numer = np.power((-x + 1), (2.0 - lam)) - 1.0
            return -numer / denom

        # Case 4: x < 0 and lambda is two
        return -log(-x + 1)