pytorch 数据加载的2种方法

旧城等待， 2022-03-09 09:35 328阅读 0赞

### 一. 封装成类Dataset，再用加载器Dataloader ###

1.封装成类Dataset：

数据集合转化成Dataset这个类，然后必须有   
\_\_init\_\_来加载数据集，   
\_\_len\_\_来获取数据集的数据数量，用于for循环的次数，   
\_\_getitem\_\_来索引数据集中的某条数据

import torch
    import os
    import torch.nn as nn
    from torchvision import transforms
    from torch.utils.data import Dataset
    from PIL import Image
    
    class GetData(Dataset):
        def __init__(self,path0,path1): #得到名字list
            super(GetData,self).__init__()
            self.path0 = path0
            self.path1 = path1
            self.name0_list = os.listdir(self.path0)
            self.name1_list = os.listdir(self.path1)
            self.img2data = transforms.Compose([transforms.ToTensor()])
    
        def __len__(self):
            return len(self.name0_list)
    
        def __getitem__(self, index): #按名取图,index对应批次
            self.name0 = self.name0_list[index]
            self.name1 = self.name1_list[index]
            img0 = Image.open(os.path.join(self.path0, self.name0))
            img1 = Image.open(os.path.join(self.path1, self.name1))
            imgdata0 = self.img2data(img0)
            imgdata1 = self.img2data(img1)
    
            return imgdata0, imgdata1

class Trainer(nn.Module):
        def __init__(self):
            super(Trainer,self).__init__()
    
            self.main_net = MainNet()
            self.main_net.cuda()#主网络加cuda，就相当于里面的所有网络加了cuda
    
            '涉及2种损失，自然就会有对应2个优化器做反向传播'
            vae_parameters = []
            vae_parameters.extend(self.main_net.encoder.parameters())
            vae_parameters.extend(self.main_net.decoder.parameters())
    
            self.opt_dis = torch.optim.Adam(self.main_net.discriminator.parameters(), lr=1e-3)
            self.opt_vae = torch.optim.Adam(vae_parameters, lr=1e-3)
    
        def train(self):
            for epoch in range(10000):
    
                if os.path.exists('encoder.pkl'):
                    self.main_net.encoder.load_state_dict(torch.load('encoder.pkl'))
                if os.path.exists('decoder.pkl'):
                    self.main_net.decoder.load_state_dict(torch.load('decoder.pkl'))
                if os.path.exists('discriminator.pkl'):
                    self.main_net.discriminator.load_state_dict(torch.load('discriminator.pkl'))
    
                self.dataloader = DataLoader(dataset.GetData(path0=r'C:\Users\87419\Desktop\cg1\64',
                                 path1=r'C:\Users\87419\Desktop\cg1\dama_64'), batch_size=128, shuffle=True)
                count = 0
    
                '每个epoch内都是遍历5万张图，即dataloader数。每count一次，即每次循环都是处理batchsize张'
                'dataloader长度 = 总张数/批次数 ：782 = 50000/64。即loader长度等于每个ecpoch的总count数'
                for img0data, img1data in self.dataloader:
    
                    img0data = img0data.cuda()#把输入的数据加cuda，接下来里面的过程数据自然也就以cuda运行
                    img1data = img1data.cuda()
    
                    count += 1
                    print(count)

import torch
    import os
    import numpy as np
    import cv2
    from torch.utils.data import Dataset,DataLoader
     
    class GetData(Dataset):
        def __init__(self,path1,path2):
            super(GetData,self).__init__()
            self.path1 = path1
            self.path2 = path2
            self.dataset1 = []
            self.dataset2 = []
            self.dataset1.extend(open(os.path.join(self.path1,'label.txt')).readlines())
            self.dataset2.extend(open(os.path.join(self.path2,'label.txt')).readlines())
     
        def __getitem__(self, index): #index不是待赋参量，而是对应批次batch_size
            str1 = self.dataset1[index].strip() #如dataset[0]是第一批次
            str2 = self.dataset2[index].strip()
            imgpath1 = os.path.join(self.path1,str1)
            imgpath2 = os.path.join(self.path2,str2)
            im1 = cv2.imread(imgpath1)
            im2 = cv2.imread(imgpath2)
            imgdata1 = torch.Tensor((im1 / 255. - 0.5))
            imgdata2 = torch.Tensor((im2 / 255. - 0.5))
            return imgdata1,imgdata2
     
        def __len__(self):
            return len(self.dataset1)

2.再用加载器Dataloader

for i in range(EPOCHES):
        print('epoch:',i)
        dataset = GetData(r'C:\Users\87419\Desktop\VAE1\data\trainB', r'C:\Users\87419\Desktop\VAE1\data\trainA')
     
        dataloader = DataLoader(dataset, batch_size=BATCH_SIZE, shuffle=True)
        for j,(imgdata1,imgdata2) in enumerate(dataloader):
          
            imgdata1_ = imgdata1.cuda()
            imgdata2_ = imgdata2.cuda()

### 二. 用torchviosion ###

import torch
    from torchvision import transforms, datasets
    from torch.utils.data import DataLoader
    
    transform1 = transforms.Compose([
            transforms.Resize(256),
            transforms.ToTensor(),
            transforms.Normalize((0.5,0.5,0.5), (0.5,0.5,0.5))
        ])
    dataset = datasets.ImageFolder(root=r'C:\Users\87419\Desktop\VAE\faces',transform=transform1)
    dataset_loader = DataLoader(dataset,batch_size=4, shuffle=True)

或定义数据加载函数：

def sample_data(path,batch_size,size=4):
        transform = transforms.Compose([transforms.Resize(size),
                                       transforms.ToTensor(),
                                       transforms.Normalize((0.5,0.5,0.5),(0.5,0.5,0.5))])
        dataset = datasets.ImageFolder(path,transform=transform)
        dataloader = DataLoader(dataset,batch_size=batch_size,shuffle=True)
    
        return dataloader

data_transforms = {
        'train': transforms.Compose([
            transforms.RandomResizedCrop(224), #Random cutting of an image (224, 224) from the original image
            transforms.RandomHorizontalFlip(), #Reversal at 0.5 probability level
            transforms.ToTensor(),  #Convert a PIL. Image with a range of [0,255] or numpy. ndarray to a shape of [C, H, W], and a FloadTensor with a range of [0,1.0].
            transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225]) #Normalization
        ]),
        'val': transforms.Compose([
            transforms.Resize(256),
            transforms.CenterCrop(224),
            transforms.ToTensor(),
            transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
        ]),
    }
     
    #image data file
    data_root = ''
    image_datasets = {x: datasets.ImageFolder(os.path.join(data_root, x),
                                              data_transforms[x]) for x in ['train', 'val']}
    # wrap your data and label into Tensor
    dataloders = {x: torch.utils.data.DataLoader(image_datasets[x],
                                                 batch_size=10,
                                                 shuffle=True,
                                                 num_workers=4) for x in ['train', 'val']}