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wassname
48 lines
1.7 KiB
Python
48 lines
1.7 KiB
Python
# Copyright (c) 2022, salesforce.com, inc.
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# All rights reserved.
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# SPDX-License-Identifier: BSD-3-Clause
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# For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/BSD-3-Clause
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from typing import Optional
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import torch
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from torch import Tensor
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from torch import nn
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import torch.nn.functional as F
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class RidgeRegressor(nn.Module):
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def __init__(self, lambda_init: Optional[float] =0.):
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super().__init__()
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self._lambda = nn.Parameter(torch.as_tensor(lambda_init, dtype=torch.float))
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def forward(self, reprs: Tensor, x: Tensor, reg_coeff: Optional[float] = None) -> Tensor:
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if reg_coeff is None:
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reg_coeff = self.reg_coeff()
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w, b = self.get_weights(reprs, x, reg_coeff)
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return w, b
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def get_weights(self, X: Tensor, Y: Tensor, reg_coeff: float) -> Tensor:
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batch_size, n_samples, n_dim = X.shape
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ones = torch.ones(batch_size, n_samples, 1, device=X.device)
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X = torch.concat([X, ones], dim=-1)
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if n_samples >= n_dim:
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# standard
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A = torch.bmm(X.transpose(-2, -1), X)
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A.diagonal(dim1=-2, dim2=-1).add_(reg_coeff)
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B = torch.bmm(X.transpose(-2, -1), Y)
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weights = torch.linalg.solve(A, B)
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else:
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# Woodbury
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# A = torch.bmm(X, X.mT)
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A = torch.bmm(X, X.transpose(-2, -1))
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A.diagonal(dim1=-2, dim2=-1).add_(reg_coeff)
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# weights = torch.bmm(X.mT, torch.linalg.solve(A, Y))
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weights = torch.bmm(X.transpose(-2, -1), torch.linalg.solve(A, Y))
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return weights[:, :-1], weights[:, -1:]
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def reg_coeff(self) -> Tensor:
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return F.softplus(self._lambda)
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