TypeError: unsupported format string passed to Tensor.__format__
When trying to convert a code written for old PyTorch to 1.9 I get this error:
(fashcomp) [jalal@goku fashion-compatibility]$ python main.py --name test_baseline --learned --l2_embed --datadir ../../../data/fashion/
/scratch3/venv/fashcomp/lib/python3.8/site-packages/torchvision/transforms/transforms.py:310: UserWarning: The use of the transforms.Scale transform is deprecated, please use transforms.Resize instead.
  warnings.warn(&quot;The use of the transforms.Scale transform is deprecated, &quot; +
  + Number of params: 3191808
&lt;class 'torch.utils.data.dataloader.DataLoader'&gt;
/scratch3/venv/fashcomp/lib/python3.8/site-packages/torch/nn/functional.py:718: UserWarning: Named tensors and all their associated APIs are an experimental feature and subject to change. Please do not use them for anything important until they are released as stable. (Triggered internally at  /pytorch/c10/core/TensorImpl.h:1156.)
  return torch.max_pool2d(input, kernel_size, stride, padding, dilation, ceil_mode)
Traceback (most recent call last):
  File &quot;main.py&quot;, line 329, in &lt;module&gt;
    main()    
  File &quot;main.py&quot;, line 167, in main
    train(train_loader, tnet, criterion, optimizer, epoch)
  File &quot;main.py&quot;, line 240, in train
    print('Train Epoch: {} [{}/{}]\t'
  File &quot;/scratch3/venv/fashcomp/lib/python3.8/site-packages/torch/_tensor.py&quot;, line 561, in __format__
    return object.__format__(self, format_spec)
TypeError: unsupported format string passed to Tensor.__format__

Here's the problematic part of the code:
if batch_idx % args.log_interval == 0:
    print('Train Epoch: {} [{}/{}]\t'
          'Loss: {:.4f} ({:.4f}) \t'
          'Acc: {:.2f}% ({:.2f}%) \t'
          'Emb_Norm: {:.2f} ({:.2f})'.format(
        epoch, batch_idx * num_items, len(train_loader.dataset),
        losses.val, losses.avg, 
        100. * accs.val, 100. * accs.avg, emb_norms.val, emb_norms.avg))

I see from this bug report that, as of two years ago, there was no solution provided to this problem. Do you have any suggestions on how to fix this, or an alternative of any sort?
Code is from here.

This error is reproducible if you try to format a torch.Tensor in a specific way:
&gt;&gt;&gt; print('{:.2f}'.format(torch.rand(1)))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
&lt;ipython-input-3-ece663be5b5c&gt; in &lt;module&gt;()
----&gt; 1 print('{:.2f}'.format(torch.tensor([1])))

/usr/local/lib/python3.7/dist-packages/torch/_tensor.py in __format__(self, format_spec)
    559         if self.dim() == 0:
    560             return self.item().__format__(format_spec)
--&gt; 561         return object.__format__(self, format_spec)
    562 
    563     def __ipow__(self, other):  # type: ignore[misc]

TypeError: unsupported format string passed to Tensor.__format__

Doing '{}'.format(torch.tensor(1)) - i.e. without any formating rule - will work.
This is because torch.Tensor doesn't implement those specific format operations.

An easy fix would be to convert the torch.Tensor to the appropriate - corresponding - type using item:
&gt;&gt;&gt; print('{:.2f}'.format(torch.rand(1).item()))
0.02

You should apply this modification to all torch.Tensor involved in your print string expression: losses.val, losses.avg, accs.val, accs.avg, emb_norms.val, and emb_norms.avg?
