如何使用 torch vision 在 Google Colab 上加载 CelebA 数据集,而不 运行 内存不足?

How do I load the CelebA dataset on Google Colab, using torch vision, without running out of memory?

我正在学习 DCGAN 上的教程。每当我尝试加载 CelebA 数据集时,torchvision 都会用完我所有 运行-time 的内存 (12GB) 并且 运行time 崩溃。我正在寻找如何加载和应用转换到数据集的方法,而不会占用我 运行-time 的资源。

复制

这是导致问题的代码部分。

# Root directory for the dataset
data_root = 'data/celeba'
# Spatial size of training images, images are resized to this size.
image_size = 64

celeba_data = datasets.CelebA(data_root,
                              download=True,
                              transform=transforms.Compose([
                                  transforms.Resize(image_size),
                                  transforms.CenterCrop(image_size),
                                  transforms.ToTensor(),
                                  transforms.Normalize(mean=[0.5, 0.5, 0.5],
                                                       std=[0.5, 0.5, 0.5])
                              ]))

可以找到完整的笔记本here

环境

相关库的版本:

其他上下文

我尝试过的一些事情是:

# Download the dataset only
datasets.CelebA(data_root, download=True)
# Load the dataset here
celeba_data = datasets.CelebA(data_root, download=False, transforms=...)
# Download the dataset only
datasets.CelebA(data_root, download=True)
# Load the dataset using the ImageFolder class
celeba_data = datasets.ImageFolder(data_root, transforms=...)

在这两种情况下,内存问题仍然存在。

尝试以下操作:

from torchvision.datasets import ImageFolder
from torch.utils.data import DataLoader
from torchvision import transforms

# Root directory for the dataset
data_root = 'data/celeba'
# Spatial size of training images, images are resized to this size.
image_size = 64
# batch size
batch_size = 10

transform=transforms.Compose([
                              transforms.Resize(image_size),
                              transforms.CenterCrop(image_size),
                              transforms.ToTensor(),
                              transforms.Normalize(mean=[0.5, 0.5, 0.5],
                                                   std=[0.5, 0.5, 0.5])

dataset = ImageFolder(data_root, transform)

data_loader = DataLoader(dataset=dataset, batch_size=batch_size, shuffle=True, num_workers=8, drop_last=True)

Dataloader class 的更多详细信息可以查找 here。 以上回答,礼貌 this kaggle notebook.

我没能找到内存问题的解决方案。但是,我想出了一个解决方法,即自定义数据集。这是我的实现:

import os
import zipfile 
import gdown
import torch
from natsort import natsorted
from PIL import Image
from torch.utils.data import Dataset
from torchvision import transforms

## Setup
# Number of gpus available
ngpu = 1
device = torch.device('cuda:0' if (
    torch.cuda.is_available() and ngpu > 0) else 'cpu')

## Fetch data from Google Drive 
# Root directory for the dataset
data_root = 'data/celeba'
# Path to folder with the dataset
dataset_folder = f'{data_root}/img_align_celeba'
# URL for the CelebA dataset
url = 'https://drive.google.com/uc?id=1cNIac61PSA_LqDFYFUeyaQYekYPc75NH'
# Path to download the dataset to
download_path = f'{data_root}/img_align_celeba.zip'

# Create required directories 
if not os.path.exists(data_root):
  os.makedirs(data_root)
  os.makedirs(dataset_folder)

# Download the dataset from google drive
gdown.download(url, download_path, quiet=False)

# Unzip the downloaded file 
with zipfile.ZipFile(download_path, 'r') as ziphandler:
  ziphandler.extractall(dataset_folder)

## Create a custom Dataset class
class CelebADataset(Dataset):
  def __init__(self, root_dir, transform=None):
    """
    Args:
      root_dir (string): Directory with all the images
      transform (callable, optional): transform to be applied to each image sample
    """
    # Read names of images in the root directory
    image_names = os.listdir(root_dir)

    self.root_dir = root_dir
    self.transform = transform 
    self.image_names = natsorted(image_names)

  def __len__(self): 
    return len(self.image_names)

  def __getitem__(self, idx):
    # Get the path to the image 
    img_path = os.path.join(self.root_dir, self.image_names[idx])
    # Load image and convert it to RGB
    img = Image.open(img_path).convert('RGB')
    # Apply transformations to the image
    if self.transform:
      img = self.transform(img)

    return img

## Load the dataset 
# Path to directory with all the images
img_folder = f'{dataset_folder}/img_align_celeba'
# Spatial size of training images, images are resized to this size.
image_size = 64
# Transformations to be applied to each individual image sample
transform=transforms.Compose([
    transforms.Resize(image_size),
    transforms.CenterCrop(image_size),
    transforms.ToTensor(),
    transforms.Normalize(mean=[0.5, 0.5, 0.5],
                          std=[0.5, 0.5, 0.5])
])
# Load the dataset from file and apply transformations
celeba_dataset = CelebADataset(img_folder, transform)

## Create a dataloader 
# Batch size during training
batch_size = 128
# Number of workers for the dataloader
num_workers = 0 if device.type == 'cuda' else 2
# Whether to put fetched data tensors to pinned memory
pin_memory = True if device.type == 'cuda' else False

celeba_dataloader = torch.utils.data.DataLoader(celeba_dataset,
                                                batch_size=batch_size,
                                                num_workers=num_workers,
                                                pin_memory=pin_memory,
                                                shuffle=True)

这个实现是内存高效的,适用于我的用例,即使在训练期间使用的内存平均约为 (4GB)。但是,我希望进一步了解可能导致内存问题的原因。