pytorch的pth模型转换为onnx

---

前言

将pytorch的pth模型转换为onnx

---

提示：以下是本篇文章正文内容，下面案例可供参考

一、ONNX是什么？

Open Neural Network Exchange（ONNX，开放神经网络交换）格式，是一个用于表示深度学习模型的标准，可使模型在不同框架之间进行转移，ONNX是一种针对机器学习所设计的开放式的文件格式，用于存储训练好的模型。它使得不同的人工智能框架（如Pytorch, MXNet）可以采用相同格式存储模型数据并交互。

二、使用方法

import cv2
import torch
from models.CC import CrowdCounter
from torch.autograd import Variable
import torchvision.transforms as standard_transforms


def pth_to_onnx():
    net= CrowdCounter([0], 'res50') #加载神经网络
    #注意查看net的结构
    pthfile = '/vgg16.pth'  #输入pth模型
    model_test = torch.load(pthfile)  ##加载多卡训练后的pth模型
    net.load_state_dict({k.replace(k, 'CCN.' + k): v for k, v in model_test.items()})
    net.cuda()
    net.eval()
    image = cv2.imread('test1.jpg')
    img = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
    img = img_transform(img)
    img = img.view(1, img.shape[0], img.shape[1], img.shape[2])
    with torch.no_grad():  #不需要降低梯度
        img = Variable(img).cuda()
    input_names = ["feature4"]  #只代表输入节点名称
    output_names = ["de_pred"]  #只代表输出节点名称
    #只能输入卷积网络的内容，类似回归损失之类的除外
    torch.onnx.export(net.CCN, img, "res50.onnx", verbose=True, input_names=input_names,
                      output_names=output_names)
                    
```bash
Res50(
#   (de_pred): Sequential(
#     (0): Conv2d(
#       (conv): Conv2d(1024, 128, kernel_size=(1, 1), stride=(1, 1))
#       (relu): ReLU(inplace=True)
#     )
#     (1): Conv2d(
#       (conv): Conv2d(128, 1, kernel_size=(1, 1), stride=(1, 1))
#       (relu): ReLU(inplace=True)
#     )
#   )
#   (frontend): Sequential(
#     (0): Conv2d(3, 64, kernel_size=(7, 7), stride=(2, 2), padding=(3, 3), bias=False)
#     (1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#     (2): ReLU(inplace=True)
#     (3): MaxPool2d(kernel_size=3, stride=2, padding=1, dilation=1, ceil_mode=False)
#     (4): Sequential(
#       (0): Bottleneck(
#         (conv1): Conv2d(64, 64, kernel_size=(1, 1), stride=(1, 1), bias=False)
#         (bn1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (conv2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
#         (bn2): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (conv3): Conv2d(64, 256, kernel_size=(1, 1), stride=(1, 1), bias=False)
#         (bn3): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (relu): ReLU(inplace=True)
#         (downsample): Sequential(
#           (0): Conv2d(64, 256, kernel_size=(1, 1), stride=(1, 1), bias=False)
#           (1): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         )
#       )
#       (1): Bottleneck(
#
#       )
#       (2): Bottleneck(
#         (conv1): Conv2d(256, 64, kernel_size=(1, 1), stride=(1, 1), bias=False)
#         (bn1): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (conv2): Conv2d(64, 64, kernel_size=(3, 3), stride=(1, 1), padding=(1, 1), bias=False)
#         (bn2): BatchNorm2d(64, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (conv3): Conv2d(64, 256, kernel_size=(1, 1), stride=(1, 1), bias=False)
#         (bn3): BatchNorm2d(256, eps=1e-05, momentum=0.1, affine=True, track_running_stats=True)
#         (relu): ReLU(inplace=True)
#       )
#     )
#     (5): Sequential(
#       (0): Bottleneck(
#         (conv1): Conv2d(256, 128, kernel_size=(1, 

总结

上述代码可以很方便的转换pth为onnx结构，需要注意torch.onnx.export中输入的网络