Anyone , Please help to solve this error

[MCA-eng]

File "train.py", line 329, in
main()
File "train.py", line 116, in main
epoch=epoch)
File "train.py", line 184, in train
loss += alpha_c * ((1. - alphas.sum(dim=1)) ** 2).mean()
UnboundLocalError: local variable 'loss' referenced before assignment

[secretsather]

Have you modified the code in any way?

[MCA-eng]

Epoch: [0][17100/17702] Batch Time 0.232 (0.242) Data Load Time 0.000 (0.000) Loss 0.8871 (0.8864) Top-5 Accuracy 0.000 (with change of loss variable , getting this error

Epoch: [0][17200/17702] Batch Time 0.237 (0.242) Data Load Time 0.000 (0.000) Loss 0.8892 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17300/17702] Batch Time 0.224 (0.242) Data Load Time 0.000 (0.000) Loss 0.8847 (0.8864) Top-5 Accuracy 0.000 (0.025)
Epoch: [0][17400/17702] Batch Time 0.228 (0.242) Data Load Time 0.000 (0.000) Loss 0.8909 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17500/17702] Batch Time 0.239 (0.242) Data Load Time 0.000 (0.000) Loss 0.8889 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17600/17702] Batch Time 0.251 (0.242) Data Load Time 0.000 (0.000) Loss 0.8868 (0.8864) Top-5 Accuracy 0.273 (0.024)
Epoch: [0][17700/17702] Batch Time 0.232 (0.242) Data Load Time 0.000 (0.000) Loss 0.8859 (0.8864) Top-5 Accuracy 0.271 (0.024)
Traceback (most recent call last):
File "train.py", line 328, in
main()
File "train.py", line 122, in main
criterion=criterion)
File "train.py", line 272, in validate
loss = criterion(scores, targets)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/modules/module.py", line 1102, in _call_impl
return forward_call(*input, **kwargs)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/modules/loss.py", line 1152, in forward
label_smoothing=self.label_smoothing)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/functional.py", line 2846, in cross_entropy
return torch._C._nn.cross_entropy_loss(input, target, weight, _Reduction.get_enum(reduction), ignore_index, label_smoothing)
TypeError: cross_entropy_loss(): argument 'input' (position 1) must be Tensor, not PackedSequence

Yes,
train.py is :

import time
import torch.backends.cudnn as cudnn
import torch.optim
import torch.utils.data
import torchvision.transforms as transforms
from torch import nn
from torch.nn.utils.rnn import pack_padded_sequence
from models import Encoder, DecoderWithAttention
from datasets import *
from utils import *
from nltk.translate.bleu_score import corpus_bleu

Data parameters

data_folder = 'media/ssd/caption data' # folder with data files saved by create_input_files.py
data_name = 'coco_5_cap_per_img_5_min_word_freq' # base name shared by data files

Model parameters

emb_dim = 512 # dimension of word embeddings
attention_dim = 512 # dimension of attention linear layers
decoder_dim = 512 # dimension of decoder RNN
dropout = 0.5
device = torch.device("cuda" if torch.cuda.is_available() else "cpu") # sets device for model and PyTorch tensors
cudnn.benchmark = True # set to true only if inputs to model are fixed size; otherwise lot of computational overhead

Training parameters

start_epoch = 0
epochs = 120 # number of epochs to train for (if early stopping is not triggered)
epochs_since_improvement = 0 # keeps track of number of epochs since there's been an improvement in validation BLEU
batch_size = 32
workers = 1 # for data-loading; right now, only 1 works with h5py
encoder_lr = 1e-4 # learning rate for encoder if fine-tuning
decoder_lr = 4e-4 # learning rate for decoder
grad_clip = 5. # clip gradients at an absolute value of
alpha_c = 1. # regularization parameter for 'doubly stochastic attention', as in the paper
best_bleu4 = 0. # BLEU-4 score right now
print_freq = 100 # print training/validation stats every __ batches
fine_tune_encoder = False # fine-tune encoder?
checkpoint = None # path to checkpoint, None if none

def main():
"""
Training and validation.
"""

global best_bleu4, epochs_since_improvement, checkpoint, start_epoch, fine_tune_encoder, data_name, word_map

# Read word map
word_map_file = os.path.join(data_folder, 'WORDMAP_' + data_name + '.json')
with open(word_map_file, 'r') as j:
    word_map = json.load(j)

# Initialize / load checkpoint
if checkpoint is None:
    decoder = DecoderWithAttention(attention_dim=attention_dim,
                                   embed_dim=emb_dim,
                                   decoder_dim=decoder_dim,
                                   vocab_size=len(word_map),
                                   dropout=dropout)
    decoder_optimizer = torch.optim.Adam(params=filter(lambda p: p.requires_grad, decoder.parameters()),
                                         lr=decoder_lr)
    encoder = Encoder()
    encoder.fine_tune(fine_tune_encoder)
    encoder_optimizer = torch.optim.Adam(params=filter(lambda p: p.requires_grad, encoder.parameters()),
                                         lr=encoder_lr) if fine_tune_encoder else None

else:
    checkpoint = torch.load(checkpoint)
    start_epoch = checkpoint['epoch'] + 1
    epochs_since_improvement = checkpoint['epochs_since_improvement']
    best_bleu4 = checkpoint['bleu-4']
    decoder = checkpoint['decoder']
    decoder_optimizer = checkpoint['decoder_optimizer']
    encoder = checkpoint['encoder']
    encoder_optimizer = checkpoint['encoder_optimizer']
    if fine_tune_encoder is True and encoder_optimizer is None:
        encoder.fine_tune(fine_tune_encoder)
        encoder_optimizer = torch.optim.Adam(params=filter(lambda p: p.requires_grad, encoder.parameters()),
                                             lr=encoder_lr)

# Move to GPU, if available
decoder = decoder.to(device)
encoder = encoder.to(device)

# Loss function
criterion = nn.CrossEntropyLoss().to(device)

# Custom dataloaders
normalize = transforms.Normalize(mean=[0.485, 0.456, 0.406],
                                 std=[0.229, 0.224, 0.225])
train_loader = torch.utils.data.DataLoader(
    CaptionDataset(data_folder, data_name, 'TRAIN', transform=transforms.Compose([normalize])),
    batch_size=batch_size, shuffle=True, num_workers=workers, pin_memory=True)
val_loader = torch.utils.data.DataLoader(
    CaptionDataset(data_folder, data_name, 'VAL', transform=transforms.Compose([normalize])),
    batch_size=batch_size, shuffle=True, num_workers=workers, pin_memory=True)

# Epochs
for epoch in range(start_epoch, epochs):

    # Decay learning rate if there is no improvement for 8 consecutive epochs, and terminate training after 20
    if epochs_since_improvement == 20:
        break
    if epochs_since_improvement > 0 and epochs_since_improvement % 8 == 0:
        adjust_learning_rate(decoder_optimizer, 0.8)
        if fine_tune_encoder:
            adjust_learning_rate(encoder_optimizer, 0.8)

    # One epoch's training
    train(train_loader=train_loader,
          encoder=encoder,
          decoder=decoder,
          criterion=criterion,
          encoder_optimizer=encoder_optimizer,
          decoder_optimizer=decoder_optimizer,
          epoch=epoch)

    # One epoch's validation
    recent_bleu4 = validate(val_loader=val_loader,
                            encoder=encoder,
                            decoder=decoder,
                            criterion=criterion)

    # Check if there was an improvement
    is_best = recent_bleu4 > best_bleu4
    best_bleu4 = max(recent_bleu4, best_bleu4)
    if not is_best:
        epochs_since_improvement += 1
        print("\nEpochs since last improvement: %d\n" % (epochs_since_improvement,))
    else:
        epochs_since_improvement = 0

    # Save checkpoint
    save_checkpoint(data_name, epoch, epochs_since_improvement, encoder, decoder, encoder_optimizer,
                    decoder_optimizer, recent_bleu4, is_best)

def train(train_loader, encoder, decoder, criterion, encoder_optimizer, decoder_optimizer, epoch):
"""
Performs one epoch's training.

:param train_loader: DataLoader for training data
:param encoder: encoder model
:param decoder: decoder model
:param criterion: loss layer
:param encoder_optimizer: optimizer to update encoder's weights (if fine-tuning)
:param decoder_optimizer: optimizer to update decoder's weights
:param epoch: epoch number
"""

decoder.train()  # train mode (dropout and batchnorm is used)
encoder.train()

batch_time = AverageMeter()  # forward prop. + back prop. time
data_time = AverageMeter()  # data loading time
losses = AverageMeter()  # loss (per word decoded)
top5accs = AverageMeter()  # top5 accuracy

start = time.time()

# Batches
for i, (imgs, caps, caplens) in enumerate(train_loader):
    data_time.update(time.time() - start)

    # Move to GPU, if available
    imgs = imgs.to(device)
    caps = caps.to(device)
    caplens = caplens.to(device)

    # Forward prop.
    imgs = encoder(imgs)
    scores, caps_sorted, decode_lengths, alphas, sort_ind = decoder(imgs, caps, caplens)

    # Since we decoded starting with <start>, the targets are all words after <start>, up to <end>
    targets = caps_sorted[:, 1:]

    # Remove timesteps that we didn't decode at, or are pads
    # pack_padded_sequence is an easy trick to do this
    scores = pack_padded_sequence(scores, decode_lengths, batch_first=True).data
    targets = pack_padded_sequence(targets, decode_lengths, batch_first=True).data

    # Calculate loss
    # Add doubly stochastic attention regularization
    loss = alpha_c * ((1. - alphas.sum(dim=1)) ** 2).mean()

    # Back prop.
    decoder_optimizer.zero_grad()
    if encoder_optimizer is not None:
        encoder_optimizer.zero_grad()
    loss.backward()

    # Clip gradients
    if grad_clip is not None:
        clip_gradient(decoder_optimizer, grad_clip)
        if encoder_optimizer is not None:
            clip_gradient(encoder_optimizer, grad_clip)

    # Update weights
    decoder_optimizer.step()
    if encoder_optimizer is not None:
        encoder_optimizer.step()

    # Keep track of metrics
    top5 = accuracy(scores, targets, 5)
    losses.update(loss.item(), sum(decode_lengths))
    top5accs.update(top5, sum(decode_lengths))
    batch_time.update(time.time() - start)

    start = time.time()

    # Print status
    if i % print_freq == 0:
        print('Epoch: [{0}][{1}/{2}]\t'
              'Batch Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
              'Data Load Time {data_time.val:.3f} ({data_time.avg:.3f})\t'
              'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
              'Top-5 Accuracy {top5.val:.3f} ({top5.avg:.3f})'.format(epoch, i, len(train_loader),
                                                                      batch_time=batch_time,
                                                                      data_time=data_time, loss=losses,
                                                                      top5=top5accs))

def validate(val_loader, encoder, decoder, criterion):
"""
Performs one epoch's validation.

:param val_loader: DataLoader for validation data.
:param encoder: encoder model
:param decoder: decoder model
:param criterion: loss layer
:return: BLEU-4 score
"""
decoder.eval()  # eval mode (no dropout or batchnorm)
if encoder is not None:
    encoder.eval()

batch_time = AverageMeter()
losses = AverageMeter()
top5accs = AverageMeter()

start = time.time()

references = list()  # references (true captions) for calculating BLEU-4 score
hypotheses = list()  # hypotheses (predictions)

# explicitly disable gradient calculation to avoid CUDA memory error
# solves the issue #57
with torch.no_grad():
    # Batches
    for i, (imgs, caps, caplens, allcaps) in enumerate(val_loader):

        # Move to device, if available
        imgs = imgs.to(device)
        caps = caps.to(device)
        caplens = caplens.to(device)

        # Forward prop.
        if encoder is not None:
            imgs = encoder(imgs)
        scores, caps_sorted, decode_lengths, alphas, sort_ind = decoder(imgs, caps, caplens)

        # Since we decoded starting with <start>, the targets are all words after <start>, up to <end>
        targets = caps_sorted[:, 1:]

        # Remove timesteps that we didn't decode at, or are pads
        # pack_padded_sequence is an easy trick to do this
        scores_copy = scores.clone()
        scores= pack_padded_sequence(scores, decode_lengths, batch_first=True)
        targets = pack_padded_sequence(targets, decode_lengths, batch_first=True)

        # Calculate loss
        loss = criterion(scores, targets)

        # Add doubly stochastic attention regularization
        loss += alpha_c * ((1. - alphas.sum(dim=1)) ** 2).mean()

        # Keep track of metrics
        losses.update(loss.item(), sum(decode_lengths))
        top5 = accuracy(scores, targets, 5)
        top5accs.update(top5, sum(decode_lengths))
        batch_time.update(time.time() - start)

        start = time.time()

        if i % print_freq == 0:
            print('Validation: [{0}/{1}]\t'
                  'Batch Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
                  'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
                  'Top-5 Accuracy {top5.val:.3f} ({top5.avg:.3f})\t'.format(i, len(val_loader), batch_time=batch_time,
                                                                            loss=losses, top5=top5accs))

        # Store references (true captions), and hypothesis (prediction) for each image
        # If for n images, we have n hypotheses, and references a, b, c... for each image, we need -
        # references = [[ref1a, ref1b, ref1c], [ref2a, ref2b], ...], hypotheses = [hyp1, hyp2, ...]

        # References
        allcaps = allcaps[sort_ind]  # because images were sorted in the decoder
        for j in range(allcaps.shape[0]):
            img_caps = allcaps[j].tolist()
            img_captions = list(
                map(lambda c: [w for w in c if w not in {word_map['<start>'], word_map['<pad>']}],
                    img_caps))  # remove <start> and pads
            references.append(img_captions)

        # Hypotheses
        _, preds = torch.max(scores_copy, dim=2)
        preds = preds.tolist()
        temp_preds = list()
        for j, p in enumerate(preds):
            temp_preds.append(preds[j][:decode_lengths[j]])  # remove pads
        preds = temp_preds
        hypotheses.extend(preds)

        assert len(references) == len(hypotheses)

    # Calculate BLEU-4 scores
    bleu4 = corpus_bleu(references, hypotheses)

    print(
        '\n * LOSS - {loss.avg:.3f}, TOP-5 ACCURACY - {top5.avg:.3f}, BLEU-4 - {bleu}\n'.format(
            loss=losses,
            top5=top5accs,
            bleu=bleu4))

return bleu4

if name == 'main':
main()

But now with the change in loss variable it is

Epoch: [0][17100/17702] Batch Time 0.232 (0.242) Data Load Time 0.000 (0.000) Loss 0.8871 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17200/17702] Batch Time 0.237 (0.242) Data Load Time 0.000 (0.000) Loss 0.8892 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17300/17702] Batch Time 0.224 (0.242) Data Load Time 0.000 (0.000) Loss 0.8847 (0.8864) Top-5 Accuracy 0.000 (0.025)
Epoch: [0][17400/17702] Batch Time 0.228 (0.242) Data Load Time 0.000 (0.000) Loss 0.8909 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17500/17702] Batch Time 0.239 (0.242) Data Load Time 0.000 (0.000) Loss 0.8889 (0.8864) Top-5 Accuracy 0.000 (0.024)
Epoch: [0][17600/17702] Batch Time 0.251 (0.242) Data Load Time 0.000 (0.000) Loss 0.8868 (0.8864) Top-5 Accuracy 0.273 (0.024)
Epoch: [0][17700/17702] Batch Time 0.232 (0.242) Data Load Time 0.000 (0.000) Loss 0.8859 (0.8864) Top-5 Accuracy 0.271 (0.024)
Traceback (most recent call last):
File "train.py", line 328, in
main()
File "train.py", line 122, in main
criterion=criterion)
File "train.py", line 272, in validate
loss = criterion(scores, targets)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/modules/module.py", line 1102, in _call_impl
return forward_call(*input, **kwargs)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/modules/loss.py", line 1152, in forward
label_smoothing=self.label_smoothing)
File "/usr/local/lib/python3.6/dist-packages/torch/nn/functional.py", line 2846, in cross_entropy
return torch._C._nn.cross_entropy_loss(input, target, weight, _Reduction.get_enum(reduction), ignore_index, label_smoothing)
TypeError: cross_entropy_loss(): argument 'input' (position 1) must be Tensor, not PackedSequence

[AndreiMoraru123]

Edit:

I think there is an exact fix for this here