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from abc import abstractmethod
from typing import Any, Tuple
import torch
import torch.nn.functional as F
from torch import nn
class AbstractRegularizer(nn.Module):
def __init__(self):
super().__init__()
def forward(self, z: torch.Tensor) -> Tuple[torch.Tensor, dict]:
raise NotImplementedError()
@abstractmethod
def get_trainable_parameters(self) -> Any:
raise NotImplementedError()
class IdentityRegularizer(AbstractRegularizer):
def forward(self, z: torch.Tensor) -> Tuple[torch.Tensor, dict]:
return z, dict()
def get_trainable_parameters(self) -> Any:
yield from ()
def measure_perplexity(
predicted_indices: torch.Tensor, num_centroids: int
) -> Tuple[torch.Tensor, torch.Tensor]:
# src: https://github.com/karpathy/deep-vector-quantization/blob/main/model.py
# eval cluster perplexity. when perplexity == num_embeddings then all clusters are used exactly equally
encodings = (
F.one_hot(predicted_indices, num_centroids).float().reshape(-1, num_centroids)
)
avg_probs = encodings.mean(0)
perplexity = (-(avg_probs * torch.log(avg_probs + 1e-10)).sum()).exp()
cluster_use = torch.sum(avg_probs > 0)
return perplexity, cluster_use
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