Source code for tensorly.random.base

import numpy as np
from ..cp_tensor import (cp_to_tensor, CPTensor,
                         cp_normalize, validate_cp_rank)
from ..tucker_tensor import tucker_to_tensor, TuckerTensor, validate_tucker_rank
from ..tt_tensor import tt_to_tensor, TTTensor, validate_tt_rank
from ..tt_matrix import tt_matrix_to_tensor, TTMatrix, validate_tt_matrix_rank
from ..parafac2_tensor import parafac2_to_tensor, Parafac2Tensor
from .. import backend as T
from ..utils import DefineDeprecated
import warnings


def random_tensor(shape, random_state=None, **context):
    """Create a random tensor
    """
    rns = T.check_random_state(random_state)
    return T.tensor(rns.random_sample(shape), **context)


[docs]def random_parafac2(shapes, rank, full=False, random_state=None, normalise_factors=True, **context): """Generate a random PARAFAC2 tensor Parameters ---------- shape : tuple A tuple where each element represents the shape of a matrix represented by the PARAFAC2 model. The second element in each shape-tuple must be constant. rank : int or int list rank of the Parafac2 decomposition full : bool, optional, default is False if True, a full tensor is returned otherwise, the decomposed tensor is returned random_state : `np.random.RandomState` """ rns = T.check_random_state(random_state) if not all(shape[1] == shapes[0][1] for shape in shapes): raise ValueError('All matrices must have equal number of columns.') projection_matrices = [ T.qr(T.tensor(rns.random_sample((shape[0], rank)), **context))[0] for shape in shapes ] weights, factors = random_cp( [len(shapes), rank, shapes[0][1]], rank=rank, normalise_factors=False, random_state=rns, **context ) parafac2_tensor = Parafac2Tensor((weights, factors, projection_matrices)) if full: return parafac2_to_tensor(parafac2_tensor) else: return parafac2_tensor
[docs]def random_cp(shape, rank, full=False, orthogonal=False, random_state=None, normalise_factors=True, **context): """Generates a random CP tensor Parameters ---------- shape : tuple shape of the tensor to generate rank : int rank of the CP decomposition full : bool, optional, default is False if True, a full tensor is returned otherwise, the decomposed tensor is returned orthogonal : bool, optional, default is False if True, creates a tensor with orthogonal components random_state : `np.random.RandomState` context : dict context in which to create the tensor Returns ------- random_cp : ND-array or 2D-array list ND-array : full tensor if `full` is True 2D-array list : list of factors otherwise """ rank = validate_cp_rank(shape, rank) if (rank > min(shape)) and orthogonal: warnings.warn('Can only construct orthogonal tensors when rank <= min(shape) but got ' 'a tensor with min(shape)={} < rank={}'.format(min(shape), rank)) rns = T.check_random_state(random_state) factors = [T.tensor(rns.random_sample((s, rank)), **context) for s in shape] weights = T.ones(rank, **context) if orthogonal: factors = [T.qr(factor)[0] for factor in factors] if full: return cp_to_tensor((weights, factors)) elif normalise_factors: return cp_normalize((weights, factors)) else: return CPTensor((weights, factors))
[docs]def random_tucker(shape, rank, full=False, orthogonal=False, random_state=None, **context): """Generates a random Tucker tensor Parameters ---------- shape : tuple shape of the tensor to generate rank : int or int list rank of the Tucker decomposition if int, the same rank is used for each mode otherwise, dimension of each mode full : bool, optional, default is False if True, a full tensor is returned otherwise, the decomposed tensor is returned orthogonal : bool, optional, default is False if True, creates a tensor with orthogonal components random_state : `np.random.RandomState` Returns ------- tucker_tensor : ND-array or (ND-array, 2D-array list) ND-array : full tensor if `full` is True (ND-array, 2D-array list) : core tensor and list of factors otherwise """ rns = T.check_random_state(random_state) rank = validate_tucker_rank(shape, rank) if orthogonal: for i, (s, r) in enumerate(zip(shape, rank)): if r > s: warnings.warn('Selected orthogonal=True, but selected a rank larger than the tensor size for mode {0}: ' 'rank[{0}]={1} > shape[{0}]={2}.'.format(i, r, s)) factors = [] for (s, r) in zip(shape, rank): if orthogonal: factor = T.tensor(rns.random_sample((s, s)), **context) Q, _= T.qr(factor) factors.append(T.tensor(Q[:, :r])) else: factors.append(T.tensor(rns.random_sample((s, r)), **context)) core = T.tensor(rns.random_sample(rank), **context) if full: return tucker_to_tensor((core, factors)) else: return TuckerTensor((core, factors))
[docs]def random_tt(shape, rank, full=False, random_state=None, **context): """Generates a random TT/MPS tensor Parameters ---------- shape : tuple shape of the tensor to generate rank : int rank of the TT decomposition must verify rank[0] == rank[-1] ==1 (boundary conditions) and len(rank) == len(shape)+1 full : bool, optional, default is False if True, a full tensor is returned otherwise, the decomposed tensor is returned random_state : `np.random.RandomState` context : dict context in which to create the tensor Returns ------- TT_tensor : ND-array or 3D-array list * ND-array : full tensor if `full` is True * 3D-array list : list of factors otherwise """ n_dim = len(shape) rank = validate_tt_rank(shape, rank) # Make sure it's not a tuple but a list rank = list(rank) # Initialization if rank[0] != 1: message = 'Provided rank[0] == {} but boundaring conditions dictatate rank[0] == rank[-1] == 1: setting rank[0] to 1.'.format(rank[0]) raise ValueError(message) if rank[-1] != 1: message = 'Provided rank[-1] == {} but boundaring conditions dictatate rank[0] == rank[-1] == 1: setting rank[-1] to 1.'.format(rank[0]) raise ValueError(message) rns = T.check_random_state(random_state) factors = [T.tensor(rns.random_sample((rank[i], s, rank[i+1])), **context)\ for i, s in enumerate(shape)] if full: return tt_to_tensor(factors) else: return TTTensor(factors)
[docs]def random_tt_matrix(shape, rank, full=False, random_state=None, **context): """Generates a random tensor in TT-Matrix format Parameters ---------- shape : tuple shape of the tensor to generate rank : int rank of the TT decomposition must verify rank[0] == rank[-1] ==1 (boundary conditions) and len(rank) == len(shape)+1 full : bool, optional, default is False if True, a full tensor is returned otherwise, the decomposed tensor is returned random_state : `np.random.RandomState` context : dict context in which to create the tensor Returns ------- TT_tensor : ND-array or 3D-array list * ND-array : full tensor if `full` is True * 3D-array list : list of factors otherwise """ n_dim = len(shape) // 2 left_shape = shape[:n_dim] right_shape = shape[n_dim:] rank = validate_tt_matrix_rank(shape, rank) factors = [] for i in range(n_dim): factors.append(random_tensor((rank[i], left_shape[i], right_shape[i], rank[i + 1]), random_state=random_state, **context)) if full: return tt_matrix_to_tensor(factors) else: return TTMatrix(factors)
random_kruskal = DefineDeprecated(deprecated_name='random_kruskal', use_instead=random_cp) random_mps = DefineDeprecated(deprecated_name='random_mps', use_instead=random_tt)