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2026-07-13 12:40:42 +08:00

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Python

# Copyright (c) 2022 PaddlePaddle 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.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations
from typing import TYPE_CHECKING
import paddle
from paddle.distribution import constraint
if TYPE_CHECKING:
from collections.abc import Sequence
from paddle import Tensor
from paddle.distribution.constraint import Constraint
class Variable:
"""Random variable of probability distribution.
Args:
is_discrete (bool): Is the variable discrete or continuous.
event_rank (int): The rank of event dimensions.
constraint (Constraint|None, optional): The constraint of the variable.
"""
def __init__(
self,
is_discrete: bool = False,
event_rank: int = 0,
constraint: Constraint | None = None,
) -> None:
self._is_discrete = is_discrete
self._event_rank = event_rank
self._constraint = constraint
@property
def is_discrete(self) -> bool:
return self._is_discrete
@property
def event_rank(self) -> int:
return self._event_rank
def constraint(self, value: Tensor) -> Tensor:
"""Check whether the 'value' meet the constraint conditions of this
random variable."""
assert self._constraint is not None
return self._constraint.check(value)
class Real(Variable):
def __init__(self, event_rank: int = 0) -> None:
super().__init__(False, event_rank, constraint.real)
class Positive(Variable):
def __init__(self, event_rank: int = 0) -> None:
super().__init__(False, event_rank, constraint.positive)
class Independent(Variable):
"""Reinterprets some of the batch axes of variable as event axes.
Args:
base (Variable): Base variable.
reinterpreted_batch_rank (int): The rightmost batch rank to be
reinterpreted.
"""
def __init__(self, base: Variable, reinterpreted_batch_rank: int) -> None:
self._base = base
self._reinterpreted_batch_rank = reinterpreted_batch_rank
super().__init__(
base.is_discrete, base.event_rank + reinterpreted_batch_rank
)
def constraint(self, value: Tensor) -> Tensor:
ret = self._base.constraint(value)
if ret.dim() < self._reinterpreted_batch_rank:
raise ValueError(
f"Input dimensions must be equal or grater than {self._reinterpreted_batch_rank}"
)
return ret.reshape(
(*ret.shape[: ret.dim() - self.reinterpreted_batch_rank], -1)
).all(-1)
class Stack(Variable):
def __init__(self, vars: Sequence[Variable], axis: int = 0) -> None:
self._vars = vars
self._axis = axis
@property
def is_discrete(self) -> bool:
return any(var.is_discrete for var in self._vars)
@property
def event_rank(self) -> int:
rank = max(var.event_rank for var in self._vars)
if self._axis + rank < 0:
rank += 1
return rank
def constraint(self, value: Tensor) -> Tensor:
if not (-value.dim() <= self._axis < value.dim()):
raise ValueError(
f'Input dimensions {value.dim()} should be grater than stack '
f'constraint axis {self._axis}.'
)
return paddle.stack(
[
var.check(value)
for var, value in zip(
self._vars, paddle.unstack(value, self._axis)
)
],
self._axis,
)
real = Real()
positive = Positive()