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