81 lines
3.2 KiB
Python
81 lines
3.2 KiB
Python
from pathlib import Path
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import numpy
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import torch
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from torch.utils.data import DataLoader, Dataset
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from torchvision.transforms import v2 as tvtrans
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import settings
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class MnistDataset(Dataset):
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"""适配PyTorch的自定义Dataset，用于加载MNIST数据。"""
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shape: int
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transform: tvtrans.Transform
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images_data: numpy.ndarray
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labels_data: torch.Tensor
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def __init__(self, images: numpy.ndarray, labels: numpy.ndarray, transform: tvtrans.Transform):
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images_len: int = images.shape[0]
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labels_len: int = labels.shape[0]
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assert (images_len == labels_len)
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self.shape = images_len
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self.images_data = images
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self.labels_data = torch.from_numpy(labels)
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self.transform = transform
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def __getitem__(self, index):
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return self.transform(self.images_data[index]), self.labels_data[index]
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def __len__(self):
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return self.shape
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class MnistDataLoaders:
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"""包含适配PyTorch的训练数据Loader和测试数据Loader的类。"""
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train_loader: DataLoader
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test_loader: DataLoader
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def __init__(self, batch_size: int):
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dataset = numpy.load(settings.MNIST_DATASET_PATH)
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# 所有图片均为黑底白字
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# 6万张训练图片：60000x28x28。标签只有第一维。
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train_images: numpy.ndarray = dataset['x_train']
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train_labels: numpy.ndarray = dataset['y_train']
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# 1万张测试图片：10000x28x28。标签只有第一维。
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test_images: numpy.ndarray = dataset['x_test']
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test_labels: numpy.ndarray = dataset['y_test']
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# 定义数据转换器
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trans = tvtrans.Compose([
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# 从uint8转换为float32并自动归一化到0-1区间
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# YYC MARK: 下面这个被标outdated了，换下面两个替代。
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# tvtrans.ToTensor(),
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tvtrans.ToImage(),
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tvtrans.ToDtype(torch.float32, scale=True),
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# 为了符合后面图像的输入颜色通道条件，要在最后挤出一个新的维度
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# YYC MARK: 上面这两步已经帮我们自动挤出那个灰度通道了。
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# tvtrans.Lambda(lambda x: x.unsqueeze(-1))
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# 这个特定的标准化参数 (0.1307, 0.3081) 是 MNIST 数据集的标准化参数，这些数值是MNIST训练集的全局均值和标准差。
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# 这种标准化有助于模型训练时的数值稳定性和收敛速度。
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# YYC MARK: 但我不想用，反正最后训练的也收敛。
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# tvtrans.Normalize((0.1307,), (0.3081,)),
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])
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# 创建数据集
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train_dataset = MnistDataset(train_images, train_labels,
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transform=trans)
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test_dataset = MnistDataset(test_images, test_labels,
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transform=trans)
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# 赋值到自身
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self.train_loader = DataLoader(dataset=train_dataset,
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batch_size=batch_size,
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shuffle=False)
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self.test_loader = DataLoader(dataset=test_dataset,
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batch_size=batch_size,
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shuffle=False)
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