vit encoder + transformer decoder model - export onnx example

refer to this code:

.

# If you want to combine a Vision Transformer (ViT) as an encoder with a Transformer-based decoder,

# you can follow the steps below.

# We will use the Hugging Face Transformers library and PyTorch.

# Install the required libraries:

# pip install torch torchvision transformers onnx

# Define the combined model:

# -----------------------------------------

import torch

import torch.nn as nn

from transformers import ViTModel, ViTConfig, AutoModelForSeq2SeqLM

class ViTTransformer(nn.Module):

def __init__(self, vit_model, transformer_decoder):

super(ViTTransformer, self).__init__()

self.vit = vit_model

self.transformer_decoder = transformer_decoder

def forward(self, x, decoder_input_ids, **kwargs):

encoder_outputs = self.vit(x)

outputs = self.transformer_decoder(decoder_input_ids, encoder_outputs=encoder_outputs, **kwargs)

return outputs

# -----------------------------------------

# Load the ViT and Transformer decoder models:

# Assuming you have a pre-trained ViT model and a pre-trained Transformer decoder model, load them as follows:

# -----------------------------------------

vit_config = ViTConfig()

vit_model = ViTModel(vit_config)

transformer_decoder = AutoModelForSeq2SeqLM.from_pretrained("your-pretrained-transformer-decoder")

# Create the combined model and load the checkpoint if you have one:

# -----------------------------------------

combined_model = ViTTransformer(vit_model, transformer_decoder)

# -----------------------------------------

# # If you have a checkpoint, load it as follows:

# # checkpoint = torch.load('path/to/checkpoint.pth')

# # combined_model.load_state_dict(checkpoint['model_state_dict'])

# Export the combined model to ONNX format:

# The process of exporting the combined model to ONNX is more complicated due to the dynamic nature of the Transformer-based decoder.

# You might need to modify the export code depending on your specific use case.

# However, here is a general example:

# -----------------------------------------

# # Set the combined model to evaluation mode

combined_model.eval()

# Create dummy input tensors with the correct dimensions

# (B x C x H x W) for image input and (B x seq_len) for decoder input

dummy_image_input = torch.randn(1, 3, 224, 224)

dummy_decoder_input = torch.randint(0, transformer_decoder.config.vocab_size, (1, 5))

# Export the combined model to ONNX format

torch.onnx.export(

combined_model,

(dummy_image_input, dummy_decoder_input),

"vit_transformer.onnx",

input_names=["image_input", "decoder_input"],

output_names=["output"],

dynamic_axes={

"image_input": {0: "batch_size"},

"decoder_input": {0: "batch_size", 1: "sequence_length"},

"output": {0: "batch_size", 1: "sequence_length"},

},

opset_version=12,

)

# -----------------------------------------

# This code will create an ONNX file (vit_transformer.onnx) containing the combined ViT and Transformer decoder model.

# Note that you might need to adjust the code according to the specific needs of your application.

..

Thank you.🙇🏻‍♂️