Source code for netket.hilbert.abstract_hilbert

# Copyright 2021 The NetKet Authors - All rights reserved.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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import abc

from typing import Tuple, Optional, Union, Iterable

import jax.numpy as jnp
import numpy as np

max_states = np.iinfo(np.int32).max
"""int: Maximum number of states that can be indexed"""

class AbstractHilbert(abc.ABC):
    """Abstract class for NetKet hilbert objects.

    This class defines the common interface used to interact with Hilbert spaces.

    An AbstractHilbert object identifies an Hilbert space and a computational basis on
    such hilbert space, such as the z-basis for spins on a lattice, or the
    position-basis for particles in a box.

    Hilbert Spaces are generally immutable python objects that must be hashable in order
    to be used as static arguments to `jax.jit` functions.

    def __init__(self):
        self._hash = None

    def size(self) -> int:
        r"""The number number of degrees of freedom in the basis of this
        Hilbert space."""
        raise NotImplementedError()  # pragma: no cover

[docs] def random_state( self, key=None, size: Optional[int] = None, dtype=np.float32, ) -> jnp.ndarray: r"""Generates either a single or a batch of uniformly distributed random states. Runs as :code:`random_state(self, key, size=None, dtype=np.float32)` by default. Args: key: rng state from a jax-style functional generator. size: If provided, returns a batch of configurations of the form :code:`(size, N)` if size is an integer or :code:`(*size, N)` if it is a tuple and where :math:`N` is the Hilbert space size. By default, a single random configuration with shape :code:`(#,)` is returned. dtype: DType of the resulting vector. Returns: A state or batch of states sampled from the uniform distribution on the hilbert space. Example: >>> import netket, jax >>> hi = netket.hilbert.Qubit(N=2) >>> k1, k2 = jax.random.split(jax.random.PRNGKey(1)) >>> print(hi.random_state(key=k1)) [1. 0.] >>> print(hi.random_state(key=k2, size=2)) [[0. 0.] [0. 1.]] """ from netket.hilbert import random return random.random_state(self, key, size, dtype=dtype)
[docs] def ptrace(self, sites: Union[int, Iterable]) -> "AbstractHilbert": """Returns the hilbert space without the selected sites. Not all hilbert spaces support this operation. Args: sites: a site or list of sites to trace away Returns: The partially-traced hilbert space. The type of the resulting hilbert space might be different from the starting one. """ raise NotImplementedError("Ptrace not implemented for this hilbert space type.")
@property def is_indexable(self) -> bool: """Whether the space can be indexed with an integer""" return False @property @abc.abstractmethod def _attrs(self) -> Tuple: """ Tuple of hashable attributes, used to compute the immutable hash of this Hilbert space """ def __eq__(self, other) -> bool: if isinstance(other, type(self)): return self._attrs == other._attrs return False def __hash__(self): if self._hash is None: self._hash = hash(self._attrs) return self._hash