{"id":40830,"date":"2025-05-30T11:16:13","date_gmt":"2025-05-30T03:16:13","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/40830.html"},"modified":"2025-05-30T11:16:13","modified_gmt":"2025-05-30T03:16:13","slug":"python%e6%89%93%e5%8d%a1day38","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/40830.html","title":{"rendered":"python\u6253\u5361day38"},"content":{"rendered":"

Dataset\u548cDataloader\u7c7b<\/span><\/h2>\n
  • Dataset\u7c7b\u7684__getitem__\u548c__len__\u65b9\u6cd5（\u672c\u8d28\u662fpython\u7684\u7279\u6b8a\u65b9\u6cd5）<\/span><\/li>\n
  • Dataloader\u7c7b<\/span><\/li>\n
  • minist\u624b\u5199\u6570\u636e\u96c6\u7684\u4e86\u89e3<\/span><\/li>\n

    \u4f5c\u4e1a：<\/span><\/span>\u4e86\u89e3\u4e0bcifar\u6570\u636e\u96c6，\u5c1d\u8bd5\u83b7\u53d6\u5176\u4e2d\u4e00\u5f20\u56fe\u7247<\/span><\/p>\n

    import torch
    \nimport torchvision
    \nfrom torch.utils.data import DataLoader , Dataset # DataLoader \u662f PyTorch \u4e2d\u7528\u4e8e\u52a0\u8f7d\u6570\u636e\u7684\u5de5\u5177
    \nimport torchvision.transforms as transforms
    \nimport matplotlib.pyplot as plt
    \nimport numpy as np<\/p>\n

    # \u8bbe\u7f6e\u968f\u673a\u79cd\u5b50\u4ee5\u786e\u4fdd\u7ed3\u679c\u53ef\u91cd\u590d
    \ntorch.manual_seed(42)<\/p>\n

    transform = transforms.Compose([
    \n transforms.ToTensor(),
    \n transforms.Normalize((0.4914, 0.4822, 0.4465), (0.2470, 0.2435, 0.2616)) # CIFAR\u7684\u6807\u51c6\u5316\u53c2\u6570
    \n])
    \ntrain_dataset = torchvision.datasets.CIFAR10(
    \n root='.\/dataCIFAR', # \u6570\u636e\u5b58\u653e\u7684\u8def\u5f84
    \n train=True, # \u4f7f\u7528\u8bad\u7ec3\u96c6
    \n download=True, # \u5982\u679c\u6ca1\u6709\u6570\u636e，\u5c31\u4e0b\u8f7d
    \n transform=transform
    \n)<\/p>\n

    # \u5b9a\u4e49\u7c7b\u522b
    \nclasses = ('plane', 'car', 'bird', 'cat', 'deer',
    \n 'dog', 'frog', 'horse', 'ship', 'truck')<\/p>\n

    # \u968f\u673a\u9009\u62e9\u4e00\u5f20\u56fe\u7247
    \nidx = torch.randint(0, len(train_dataset), size=(1,))
    \nimg, label = train_dataset[idx]<\/p>\n

    # \u53cd\u6807\u51c6\u5316\u51fd\u6570
    \ndef denormalize(x):
    \n mean = torch.tensor([0.4914, 0.4822, 0.4465])
    \n std = torch.tensor([0.2470, 0.2435, 0.2616])
    \n # CIFAR-10\u662f\u5f69\u8272\u56fe\u50cf，\u9700\u8981\u5bf9\u6240\u6709\u901a\u9053\u8fdb\u884c\u53cd\u6807\u51c6\u5316
    \n return x * std[:, None, None] + mean[:, None, None]<\/p>\n

    # \u663e\u793a\u56fe\u7247
    \nplt.figure()
    \nplt.imshow(denormalize(img).permute(1, 2, 0)) # \u8c03\u6574\u901a\u9053\u987a\u5e8f\u4ee5\u6b63\u786e\u663e\u793a\u5f69\u8272\u56fe\u50cf
    \nplt.title(f'Label: {classes[label]}')
    \nplt.axis('off')
    \nplt.show()<\/p>\n

    # 3. \u521b\u5efa\u6570\u636e\u52a0\u8f7d\u5668
    \ntrain_loader = DataLoader(
    \n train_dataset,
    \n batch_size=64, # \u6bcf\u4e2a\u6279\u6b2164\u5f20\u56fe\u7247,\u4e00\u822c\u662f2\u7684\u5e42\u6b21\u65b9，\u8fd9\u4e0eGPU\u7684\u8ba1\u7b97\u6548\u7387\u6709\u5173
    \n shuffle=True # \u968f\u673a\u6253\u4e71\u6570\u636e
    \n)<\/p>\n

    \"\"<\/p>\n

    @\u6d59\u5927\u758f\u9526\u884c<\/p>\n","protected":false},"excerpt":{"rendered":"

    \u6587\u7ae0\u6d4f\u89c8\u9605\u8bfb423\u6b21\uff0c\u70b9\u8d5e7\u6b21\uff0c\u6536\u85cf4\u6b21\u3002Dataset\u7c7b\u7684__getitem__\u548c__len__\u65b9\u6cd5\uff08\u672c\u8d28\u662fpython\u7684\u7279\u6b8a\u65b9\u6cd5\uff09\u4e86\u89e3\u4e0bcifar\u6570\u636e\u96c6\uff0c\u5c1d\u8bd5\u83b7\u53d6\u5176\u4e2d\u4e00\u5f20\u56fe\u7247\u3002Dataset\u548cDataloader\u7c7b\u3002minist\u624b\u5199\u6570\u636e\u96c6\u7684\u4e86\u89e3\u3002Dataloader\u7c7b\u3002<\/p>\n","protected":false},"author":2,"featured_media":40829,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[81],"topic":[],"class_list":["post-40830","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-python"],"yoast_head":"\npython\u6253\u5361day38 - \u7f51\u7855\u4e92\u8054\u5e2e\u52a9\u4e2d\u5fc3<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.wsisp.com\/helps\/40830.html\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"python\u6253\u5361day38 - 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