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from dataclasses import dataclass
import torch
import torch.nn as nn
from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, MSELoss
from transformers import SiglipVisionModel, SiglipPreTrainedModel, SiglipVisionConfig
from transformers.utils import ModelOutput
from loss_fn import AsymmetricLossOptimized
@dataclass
class SiglipForImageClassifierOutput(ModelOutput):
loss: torch.FloatTensor | None = None
logits: torch.FloatTensor | None = None
pooler_output: torch.FloatTensor | None = None
hidden_states: tuple[torch.FloatTensor, ...] | None = None
attentions: tuple[torch.FloatTensor, ...] | None = None
class SiglipForImageClassification(SiglipPreTrainedModel):
config_class = SiglipVisionConfig
main_input_name = "pixel_values"
def __init__(
self,
config,
):
super().__init__(config)
self.num_labels = config.num_labels
self.siglip = SiglipVisionModel(config)
# Classifier head
self.classifier = (
nn.Linear(config.hidden_size, config.num_labels)
if config.num_labels > 0
else nn.Identity()
)
# Initialize weights and apply final processing
self.post_init()
def forward(
self, pixel_values: torch.FloatTensor, labels: torch.LongTensor | None = None
):
outputs = self.siglip(pixel_values)
pooler_output = outputs.pooler_output
logits = self.classifier(pooler_output)
loss = None
if labels is not None:
if self.config.problem_type is None:
if self.num_labels == 1:
self.config.problem_type = "regression"
elif self.num_labels > 1 and (
labels.dtype == torch.long or labels.dtype == torch.int
):
self.config.problem_type = "single_label_classification"
else:
self.config.problem_type = "multi_label_classification"
if self.config.problem_type == "regression":
loss_fct = MSELoss()
if self.num_labels == 1:
loss = loss_fct(logits.squeeze(), labels.squeeze())
else:
loss = loss_fct(logits, labels)
elif self.config.problem_type == "single_label_classification":
loss_fct = CrossEntropyLoss()
loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
elif self.config.problem_type == "multi_label_classification":
loss_fct = AsymmetricLossOptimized()
loss = loss_fct(logits, labels)
return SiglipForImageClassifierOutput(
loss=loss,
logits=logits,
pooler_output=outputs.pooler_output,
hidden_states=outputs.hidden_states,
attentions=outputs.attentions,
)
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