'Inplace transformation.'

def _transform(self, a):

    masked = (np.abs(a) > self.linthresh)
    sign = np.sign(a[masked])
    log = (self._linscale_adj + np.log((np.abs(a[masked]) / self.linthresh)))
    log *= (sign * self.linthresh)
    a[masked] = log
    a[(~ masked)] *= self._linscale_adj
    return a
