mparray.py 文件源码

def split(self, pos):
        """Splits the MPA into two by transforming the virtual legs into
        local legs according to :func:`vleg2leg`.

        :param pos: Number of the virtual to perform the transformation
        :returns: (mpa_left, mpa_right)

        """
        if pos < 0:
            return None, self
        elif pos >= len(self):
            return self, None

        mpa_t = self.vleg2leg(pos)
        lnorm, rnorm = mpa_t.canonical_form

        ltens_l = LocalTensors(it.islice(mpa_t.lt, 0, pos + 1),
                               cform=(min(lnorm, pos), min(rnorm, pos + 1)))
        ltens_r = LocalTensors(it.islice(mpa_t.lt, pos + 1, len(mpa_t)),
                               cform=(max(0, lnorm - pos), max(0, rnorm - pos - 1)))
        return type(self)(ltens_l), type(self)(ltens_r)