Tensor.py 文件源码

def tensordotcontract(tensors):
    '''
    Use np.tensordot to implement the contraction of tensors.

    Parameters
    ----------
    tensors : list of Tensor
        The tensors to be contracted.

    Returns
    -------
    Tensor
        The contracted tensor.
    '''
    def _contract_(a,b):
        common=set(a.labels)&set(b.labels)
        aaxes=[a.axis(label) for label in common]
        baxes=[b.axis(label) for label in common]
        labels=[label for label in it.chain(a.labels,b.labels) if label not in common]
        axes=(aaxes,baxes) if len(common)>0 else 0
        return Tensor(np.tensordot(a,b,axes=axes),labels=labels)
    result=tensors[0]
    for i in xrange(1,len(tensors)):
        result=_contract_(result,tensors[i])
    return result