I applied
transforms.RandomHorizontalFlip()
to data, but the data points remain the same in train data when I print(dataset_train).
take a look to the code.

transform_in = transforms.Compose([transforms.Grayscale(num_output_channels=1),
transforms.Resize([256, 256]),
transforms.RandomHorizontalFlip(),
transforms.ToTensor(),
transforms.Normalize(mean=[0.5], std=[0.5])])
dataset_train = dsets.ImageFolder(train_dir, transform=transform_in)
dataset_test = dsets.ImageFolder(test_dir, transform=transform_in)
print(dataset_train)

The output is the same as before transforms.RandomHorizontalFlip()