Update cifar10_tutorial.py (#1258)

small refactoring

Co-authored-by: holly1238 <77758406+holly1238@users.noreply.github.com>

Author: justOleh

beginner_source/blitz/cifar10_tutorial.py

@@ -70,14 +70,16 @@
     [transforms.ToTensor(),
      transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5))])
 
+batch_size = 4
+
 trainset = torchvision.datasets.CIFAR10(root='./data', train=True,
                                         download=True, transform=transform)
-trainloader = torch.utils.data.DataLoader(trainset, batch_size=4,
+trainloader = torch.utils.data.DataLoader(trainset, batch_size=batch_size,
                                           shuffle=True, num_workers=2)
 
 testset = torchvision.datasets.CIFAR10(root='./data', train=False,
                                        download=True, transform=transform)
-testloader = torch.utils.data.DataLoader(testset, batch_size=4,
+testloader = torch.utils.data.DataLoader(testset, batch_size=batch_size,
                                          shuffle=False, num_workers=2)
 
 classes = ('plane', 'car', 'bird', 'cat',
@@ -106,7 +108,7 @@ def imshow(img):
 # show images
 imshow(torchvision.utils.make_grid(images))
 # print labels
-print(' '.join('%5s' % classes[labels[j]] for j in range(4)))
+print(' '.join('%5s' % classes[labels[j]] for j in range(batch_size)))
 
 
 ########################################################################