text: import argparse
  import time
  import math
  import torch
  import torch.nn as nn
  import torch.onnx
  from torch.autograd import Variable
  from progress.bar import Bar
  import datatest
  import model
  import sys
  import numpy as np
  import random
  #import Decimal #TODO: need to install Decimal
  
  sys.stderr.write('Libraries loaded\n')
  
  ## Parallelization notes:
  ##   Does not currently operate across multiple nodes
  ##   Single GPU is better for default: tied,emsize:200,nhid:200,nlayers:2,dropout:0.2
  ##
  ##   Multiple GPUs are better for tied,emsize:1500,nhid:1500,nlayers:2,dropout:0.65
  ##      4 GPUs train on wikitext-2 in 1/2 - 2/3 the time of 1 GPU
  
  parser = argparse.ArgumentParser(description='PyTorch RNN/LSTM language modeling and CCG tagging multitask model')
  
  parser.add_argument('--lm_data', type=str, default=None,
                      help='location of the language modeling corpus')
  parser.add_argument('--ccg_data', type=str, default=None,
                      help='location of the CCG corpus')
  parser.add_argument('--model', type=str, default='LSTM',
                      help='type of recurrent net (RNN_TANH, RNN_RELU, LSTM, GRU)')
  parser.add_argument('--emsize', type=int, default=800,
                      help='size of word embeddings')
  parser.add_argument('--nhid', type=int, default=800,
                      help='number of hidden units per layer')
  parser.add_argument('--nlayers', type=int, default=2,
                      help='number of layers')
  parser.add_argument('--lr', type=float, default=20,
                      help='initial learning rate')
  parser.add_argument('--clip', type=float, default=0.25,
                      help='gradient clipping')
  parser.add_argument('--epochs', type=int, default=40,
                      help='upper epoch limit')
  parser.add_argument('--batch_size', type=int, default=20, metavar='N',
                      help='batch size')
  parser.add_argument('--bptt', type=int, default=35,
                      help='sequence length')
  parser.add_argument('--dropout', type=float, default=0.2,
                      help='dropout applied to layers (0 = no dropout)')
  parser.add_argument('--tied', action='store_true',
                      help='tie the word embedding and softmax weights')
  parser.add_argument('--seed', type=int, default=1111,
                      help='random seed')
  parser.add_argument('--cuda', action='store_true',
                      help='use CUDA')
  parser.add_argument('--log-interval', type=int, default=200, metavar='N',
                      help='report interval')
  parser.add_argument('--save', type=str,  default='model.pt',
                      help='path to save the final model')
  parser.add_argument('--single', action='store_true',
                      help='use only a single GPU (even if more are available)')
  parser.add_argument('--save_lm_data', type=str, default='lm_data.bin',
                      help='path to save the LM data')
  parser.add_argument('--test', action='store_true',
                      help='test a trained LM')
  parser.add_argument('--guess', action='store_true',
                      help='display best guesses at each time step')
  parser.add_argument('--guessscores', action='store_true',
                      help='display guess scores along with guesses')
  parser.add_argument('--guessratios', action='store_true',
                      help='display guess ratios normalized by best guess')
  parser.add_argument('--guessprobs', action='store_true',
                      help='display guess probs along with guesses')
  parser.add_argument('--guessn', type=int, default=1,
                      help='output top n guesses')
  parser.add_argument('--words', action='store_true',
                      help='evaluate word-level complexities (instead of sentence-level loss)')
  parser.add_argument('--trainfname', type=str, default='train.txt',
                      help='name of the training file')
  parser.add_argument('--validfname', type=str, default='valid.txt',
                      help='name of the validation file')
  parser.add_argument('--testfname', type=str, default='test.txt',
                      help='name of the test file')
  args = parser.parse_args()
  
  # Set the random seed manually for reproducibility.
  torch.manual_seed(args.seed)
  if torch.cuda.is_available():
      if not args.cuda:
          print("WARNING: You have a CUDA device, so you should probably run with --cuda")
          
      else:
          torch.cuda.manual_seed(args.seed)
  
  ###############################################################################
  # Load data
  ###############################################################################
  
  # Starting from sequential data, batchify arranges the dataset into columns.
  # For instance, with the alphabet as the sequence and batch size 4, we'd get
  #  a g m s 
  #  b h n t 
  #  c i o u 
  #  d j p v 
  #  e k q w 
  #  f l r x 
  # These columns are treated as independent by the model, which means that the
  # dependence of e. g. 'g' on 'f' can not be learned, but allows more efficient
  # batch processing.
  
  def batchify(data, bsz):
      # Work out how cleanly we can divide the dataset into bsz parts.
      if isinstance(data, tuple):
          nbatch = data[0].size(0) // bsz
          # Trim off any extra elements that wouldn't cleanly fit (remainders).
          tag_data = data[1].narrow(0, 0, nbatch * bsz)
          data = data[0].narrow(0, 0, nbatch * bsz)
          # Evenly divide the data across the bsz batches.
          tag_data = tag_data.view(bsz, -1).t().contiguous()
      else:
          nbatch = data.size(0) // bsz
          # Trim off any extra elements that wouldn't cleanly fit (remainders).
          data = data.narrow(0, 0, nbatch * bsz)
      
      # Evenly divide the data across the bsz batches.
      data = data.view(bsz, -1).t().contiguous()
      # Turning the data over to CUDA at this point may lead to more OOM errors
      #if args.cuda:
       #    data = data.cuda()
      if isinstance(data,tuple):
          return data, tag_data
      return data
      
  eval_batch_size = 10
  
  corpus = datatest.TestCorpus(args.lm_data, args.testfname, args.save_lm_data)#'/home-1/amuelle8@jhu.edu/grammars/lstm_lm.bin')
  
  if args.test:
      torch.no_grad()
      test_lm_sentences, test_lm_data, test_lm_grammatical = corpus.test_lm
  else:
      train_lm_data = batchify(corpus.train_lm, args.batch_size)
      val_lm_data = batchify(corpus.valid_lm, eval_batch_size)
      train_ccg_data = batchify(corpus.train_ccg, args.batch_size)
      val_ccg_data = batchify(corpus.valid_ccg, eval_batch_size)
      
      
  
  ###############################################################################
  # Build/load the model
  ###############################################################################
  
  if not args.test:
      ntokens = len(corpus.dictionary)
      model = model.RNNModel(args.model, ntokens, args.emsize, args.nhid, args.nlayers, args.dropout, args.tied)
      if args.cuda:
          if (not args.single) and (torch.cuda.device_count() > 1):
              # Scatters minibatches (in dim=1) across available GPUs
              model = nn.DataParallel(model,dim=1)
          model.cuda()
  
  criterion = nn.CrossEntropyLoss()
  
  ###############################################################################
  # Complexity measures
  ###############################################################################
  
  def get_entropy(o):
      ## o should be a vector scoring possible classes
      probs = nn.functional.softmax(o,dim=0)
      logprobs = nn.functional.log_softmax(o,dim=0) #numerically more stable than two separate operations
      return -1 * torch.sum(probs * logprobs)
  
  def get_surps(o):
      ## o should be a vector scoring possible classes
      logprobs = nn.functional.log_softmax(o,dim=0)
      return -1 * logprobs
  
  def get_guesses(o,scores=False):
      ## o should be a vector scoring possible classes
      guessvals, guessixes = torch.topk(o,args.guessn,0)
      # guessvals are the scores of each input cell
      # guessixes are the indices of the max cells
      if scores:
          return guessvals
      else:
          return guessixes
  
  def get_guessscores(o):
      return get_guesses(o,True)
  
  def get_complexity_iter(o,t):
      for corpuspos,targ in enumerate(t):
          word = corpus.dictionary.idx2word[targ]
          surp = get_surps(o[corpuspos])
          H = get_entropy(o[corpuspos])
          print(str(word)+' '+str(surp)+' '+str(H))
  
  def get_complexity_apply(o,t,sentid,is_grammatical,tags=False):
      ## Use apply() method
      Hs = torch.squeeze(apply(get_entropy,o))
      surps = apply(get_surps,o)
      
      if args.guess:
          guesses = apply(get_guesses, o)
          guessscores = apply(get_guessscores, o)
      ## Use dimensional indexing method
      ## NOTE: For some reason, this doesn't work.
      ##       May marginally speed things if we can determine why
      ##       Currently 'probs' ends up equivalent to o after the softmax
      #probs = nn.functional.softmax(o,dim=0)
      #logprobs = nn.functional.log_softmax(o,dim=0)
      #Hs = -1 * torch.sum(probs * logprobs),dim=1)
      #surps = -1 * logprobs
      ## Move along
      for corpuspos,targ in enumerate(t):
          if tags:
              word = corpus.dictionary.idx2tag[int(targ)]
          else:
              word = corpus.dictionary.idx2word[int(targ)]
          if word == '<eos>' or word == '<EOS>':
              #don't output the complexity of EOS
              continue
          surp = surps[corpuspos][int(targ)]
          if args.guess:
              outputguesses = []
              for g in range(args.guessn):
                  if tags:
                      outputguesses.append(corpus.dictionary.idx2tag[int(guesses[corpuspos][g])])
                  else:
                      outputguesses.append(corpus.dictionary.idx2word[int(guesses[corpuspos][g])])
                  if args.guessscores:
                      ##output raw scores
                      outputguesses.append("{:.3f}".format(float(guessscores[corpuspos][g])))
                  elif args.guessratios:
                      ##output scores (ratio of score(x)/score(best guess)
                      outputguesses.append("{:.3f}".format(float(guessscores[corpuspos][g])/float(guessscores[corpuspos][0])))
                  elif args.guessprobs:
                    ##output probabilities ## Currently normalizes probs over N-best list; ideally it'd normalize to probs before getting the N-best
                    outputguesses.append("{:.3f}".format(math.exp(float(nn.functional.log_softmax(guessscores[corpuspos],dim=0)[g]))))
              outputguesses = ' '.join(outputguesses)
              print(str(word)+' '+str(sentid)+' '+str(corpuspos)+' '+str(len(word))+' '+str(float(surp))+' '+str(float(Hs[corpuspos]))+' '+str(outputguesses)+' '+str(is_grammatical))
          else:
              print(str(word)+' '+str(sentid)+' '+str(corpuspos)+' '+str(len(word))+' '+str(float(surp))+' '+str(float(Hs[corpuspos]))+' '+str(is_grammatical))
  
  def apply(func, M):
      ## applies a function along a given dimension
      tList = [func(m) for m in torch.unbind(M,dim=0) ]
      res = torch.stack(tList)
      return res
  
  ###############################################################################
  # Training code
  ###############################################################################
  
  def repackage_hidden(h):
      """Wraps hidden states in new Variables, to detach them from their history."""
      if isinstance(h, torch.Tensor):
          return h.detach()
      else:
          return tuple(repackage_hidden(v) for v in h)
  
  # get_batch subdivides the source data into chunks of length args.bptt.
  # If source is equal to the example output of the batchify function, with
  # a bptt-limit of 2, we'd get the following two Variables for i = 0:
  #  a g m s      b h n t 
  #  b h n t      c i o u 
  # Note that despite the name of the function, the subdivison of data is not
  # done along the batch dimension (i.e. dimension 1), since that was handled
  # by the batchify function. The chunks are along dimension 0, corresponding
  # to the seq_len dimension in the LSTM.
      
  def test_get_batch(source, evaluation=False):
      if isinstance(source, tuple):
          seq_len = len(source[0]) - 1
          data = Variable(source[0][:seq_len], volatile=evaluation)
          target = Variable(source[1][:seq_len], volatile=evaluation)
          
      else:
          seq_len = len(source) - 1
          data = Variable(source[:seq_len], volatile=evaluation)
          target = Variable(source[1:1+seq_len].view(-1))
      # This is where data should be CUDA-fied to lessen OOM errors
      if args.cuda:
          return data.cuda(), target.cuda()
      else:
          return data, target
      
  def get_batch(source, i, evaluation=False):
      if isinstance(source, tuple):
          seq_len = min(args.bptt, len(source[0]) - 1 - i)
          data = Variable(source[0][i:i+seq_len], volatile=evaluation)
          target = Variable(source[1][i:i+seq_len].view(-1))
      else:
          seq_len = min(args.bptt, len(source) - 1 - i)
          data = Variable(source[i:i+seq_len], volatile=evaluation)
          target = Variable(source[i+1:i+1+seq_len].view(-1))
      #This is where data should be CUDA-fied to lessen OOM errors
      if args.cuda:
          return data.cuda(), target.cuda()
      else:
          return data, target
  
  
  def test_evaluate(test_lm_sentences, lm_data_source, test_lm_grammatical):
      # Turn on evaluation mode which disables dropout.
      model.eval()
      total_loss = 0.
      ntokens = len(corpus.dictionary)
      if args.words:
          print('word sentid sentpos wlen surp entropy grammatical')#,end='')
          if args.guess:
              for i in range(args.guessn):
                  print(' guess'+str(i))#,end='')
                  if args.guessscores:
                      print(' gscore'+str(i))#,end='')
          sys.stdout.write('\n')
      bar = Bar('Processing', max=len(lm_data_source))
      for i in range(len(lm_data_source)):
          sent_ids = lm_data_source[i]
          sent = test_lm_sentences[i]
          sent_grammatical = test_lm_grammatical[i]
          if args.cuda:
              sent_ids = sent_ids.cuda()
          #if (not args.single) and (torch.cuda.device_count() > 1):
          #    # "module" is necessary when using DataParallel
          #    hidden = model.module.init_hidden(1) # number of parallel sentences being processed
          #else:
          hidden = model.init_hidden(1) # number of parallel sentences being processed
          data, targets = test_get_batch(sent_ids, evaluation=True)
          data=data.unsqueeze(1) # only needed if there is just a single sentence being processed
          output, hidden = model(data, hidden)
          output_flat = output.view(-1, output.shape[2])
          curr_loss = criterion(output_flat, targets).item()
          #curr_loss = len(data) * criterion(output_flat, targets).data # needed if there is more than a single sentence being processed
          total_loss += curr_loss
          if args.words:
              # output word-level complexity metrics
              get_complexity_apply(output_flat,targets,i,sent_grammatical)
          else:
              # output sentence-level loss
              print(str(sent)+":"+str(curr_loss[0]))
          hidden = repackage_hidden(hidden)
          bar.next()
      bar.finish()
      return total_loss / (len(lm_data_source))
  
  def evaluate(lm_data_source):
      # Turn on evaluation mode which disables dropout.
      model.eval()
      total_loss = 0
      ntokens = len(corpus.dictionary)
      if (not args.single) and (torch.cuda.device_count() > 1):
          #"module" is necessary when using DataParallel
          hidden = model.module.init_hidden(eval_batch_size)
      else:
          hidden = model.init_hidden(eval_batch_size)
      for i in range(0, lm_data_source.size(0) - 1, args.bptt):
          data, targets = get_batch(lm_data_source, i, evaluation=True)
          output, hidden = model(data, hidden)
          output_flat = output.view(-1, ntokens)
          curr_loss = len(data) * criterion(output_flat, targets).data
          total_loss += curr_loss
          hidden = repackage_hidden(hidden)
      return total_loss / (len(lm_data_source))
  
  
  def train():
      # Turn on training mode which enables dropout.
      model.train()
      total_loss = 0
      start_time = time.time()
      ntokens = len(corpus.dictionary)
      if (not args.single) and (torch.cuda.device_count() > 1):
          # "module" is necessary when using DataParallel
          hidden = model.module.init_hidden(args.batch_size)
      else:
          hidden = model.init_hidden(args.batch_size)
      # UNCOMMENT FOR DEBUGGING
      #random.seed(10)
      order = list(enumerate(range(0, train_lm_data.size(0) + train_ccg_data.size(0) - 1, args.bptt)))
      random.shuffle(order)
      for batch, i in order:#enumerate(range(0, train_lm_data.size(0) + train_ccg_data.size(0) - 1, args.bptt)):
          # TAG
          if i > train_lm_data.size(0):
              data, targets = get_batch(train_ccg_data, i - train_lm_data.size(0))
          # LM
          else:
              data, targets = get_batch(train_lm_data, i)
              
          # Starting each batch, we detach the hidden state from how it was previously produced.
          # If we didn't, the model would try backpropagating all the way to start of the dataset.
          hidden = repackage_hidden(hidden)
          model.zero_grad()
          output, hidden = model(data, hidden)
          loss = criterion(output.view(-1, ntokens), targets)
          loss.backward()
  
          # `clip_grad_norm` helps prevent the exploding gradient problem in RNNs / LSTMs.
          torch.nn.utils.clip_grad_norm_(model.parameters(), args.clip)
          for p in model.parameters():
              p.data.add_(-lr, p.grad.data)
  
          total_loss += loss.item()#data
  
          if batch % args.log_interval == 0 and batch > 0:
              cur_loss = total_loss / args.log_interval
              elapsed = time.time() - start_time
              print('| epoch {:3d} | {:5d}/{:5d} batches | lr {:02.2f} | ms/batch {:5.2f} | '
                      'loss {:5.2f} | ppl {:8.2f}'.format(
                  epoch, batch, len(train_lm_data)+len(train_ccg_data) // args.bptt, lr,
                  elapsed * 1000 / args.log_interval, cur_loss, math.exp(cur_loss)))
              total_loss = 0
              start_time = time.time()
  
  # Loop over epochs.
  lr = args.lr
  best_val_loss = None
  
  # At any point you can hit Ctrl + C to break out of training early.
  if not args.test:
      try:
          for epoch in range(1, args.epochs+1):
              epoch_start_time = time.time()
              train()
              val_loss = evaluate(val_lm_data, val_ccg_data)
              print('-' * 89)
              print('| end of epoch {:3d} | time: {:5.2f}s | valid loss {:5.2f} | '
                    'valid ppl {:8.2f}'.format(epoch, (time.time() - epoch_start_time),
                                               val_loss, math.exp(val_loss)))
              print('-' * 89)
              # Save the model if the validation loss is the best we've seen so far.
              if not best_val_loss or val_loss < best_val_loss:
                  with open(args.save, 'wb') as f:
                      torch.save(model, f)
                      best_val_loss = val_loss
              else:
                  # Anneal the learning rate if no improvement has been seen in the validation dataset.
                  lr /= 4.0
      except KeyboardInterrupt:
          print('-' * 89)
          print('Exiting from training early')
  else:
      # Load the best saved model.
      with open(args.save, 'rb') as f:
          model = torch.load(f)
  
  
      # Run on test data.
      test_loss = test_evaluate(test_lm_sentences, test_lm_data, test_lm_grammatical)
      print('=' * 89)
      print('| End of training | test loss {:5.2f} | test ppl {:8.2f}'.format(
          test_loss, math.exp(test_loss)))
      print('=' * 89)
  