modrec-workflow/convert_to_onnx.py

import os

import numpy as np
import torch

from data.training.mobilenetv3 import mobilenetv3, RFClassifier
from onnx_files import ONNX_DIR
from helpers.app_settings import get_app_settings


def convert_to_onnx(ckpt_path, fp16=False):
    """
    Convert a PyTorch model to ONNX format.

    Parameters:
        model (torch.nn.Module): The PyTorch model to convert.
        input_shape (tuple): The shape of the input tensor.
        output_path (str): The path to save the converted ONNX model.
    """
    settings = get_app_settings()

    inference_cfg = settings.inference
    dataset_cfg = settings.dataset

    in_channels = 2
    batch_size = 1
    slice_length = int(1024 / dataset_cfg.num_slices)
    num_classes = inference_cfg.num_classes

    model = RFClassifier(
        model=mobilenetv3(
            model_size="mobilenetv3_small_050",
            num_classes=num_classes,
            in_chans=in_channels,
        )
    )

    checkpoint = torch.load(
        ckpt_path, weights_only=True, map_location=torch.device("cpu")
    )
    model.load_state_dict(checkpoint["state_dict"])

    if fp16:
        model.half()

    model.eval()

    # Generate random sample data
    base, ext = os.path.splitext(os.path.basename(ckpt_path))
    if fp16:
        output_path = os.path.join(ONNX_DIR, f"{base}_fp16.onnx")
        sample_input = torch.from_numpy(
            np.random.rand(batch_size, in_channels, slice_length).astype(np.float16)
        )
    else:
        output_path = os.path.join(ONNX_DIR, f"{base}_fp32.onnx")
        sample_input = torch.rand(batch_size, in_channels, slice_length)

    torch.onnx.export(
        model=model,
        args=sample_input,
        f=output_path,
        export_params=True,
        opset_version=20,  # Last compatible with ORT v1.15.1 is 18, 21 not supported by torch export
        do_constant_folding=True,
        input_names=["input"],
        output_names=["output"],
        dynamo=False,  # Requires onnxscript
    )


if __name__ == "__main__":
    from checkpoint_files import CHECKPOINTS_DIR

    model_checkpoint = "inference_recognition_model.ckpt"

    print("Converting to ONNX...")

    convert_to_onnx(
        ckpt_path=os.path.join(CHECKPOINTS_DIR, model_checkpoint), fp16=False
    )

    print("Conversion complete stored at: ", os.path.join(ONNX_DIR, model_checkpoint))