TuckerTensorTrain.reverse

t3toolbox.tucker_tensor_train.TuckerTensorTrain.reverse()

def reverse(self) -> 'TuckerTensorTrain':

Reverse Tucker tensor train.

Returns:

Tucker tensor train with index order reversed. shape=(N(d-1), ..., N0), tucker_ranks=(n(d-1),...,n0), tt_ranks=(1,r(d-1),...,r1,1).

Return type:

TuckerTensorTrain

Examples

>>> import numpy as np
>>> import t3toolbox.tucker_tensor_train as t3
>>> np.random.seed(0)
>>> randn = np.random.randn
>>> tucker_cores = (randn(2,3, 4,10), randn(2,3, 5,11), randn(2,3, 6,12))
>>> tt_cores = (randn(2,3, 1,4,2), randn(2,3, 2,5,3), randn(2,3, 3,6,4))
>>> x = t3.TuckerTensorTrain(tucker_cores, tt_cores)
>>> print(x.structure)
((10, 11, 12), (4, 5, 6), (1, 2, 3, 4), (2, 3))
>>> reversed_x = x.reverse()
>>> print(reversed_x.structure)             # shape, Tucker and TT ranks all reversed
((12, 11, 10), (6, 5, 4), (4, 3, 2, 1), (2, 3))
>>> x_dense = x.to_dense()
>>> reversed_x_dense = reversed_x.to_dense()
>>> x_dense2 = reversed_x_dense.transpose([0,1, 4,3,2])   # un-reverse the free axes
>>> print(np.allclose(x_dense, x_dense2))
True