class TorchRankerAgent(TorchAgent):
"""
Abstract TorchRankerAgent class; only meant to be extended.
TorchRankerAgents aim to provide convenient functionality for building ranking
models. This includes:
- Training/evaluating on candidates from a variety of sources.
- Computing hits@1, hits@5, mean reciprical rank (MRR), and other metrics.
- Caching representations for fast runtime when deploying models to production.
"""
@classmethod
def add_cmdline_args(cls, argparser):
"""
Add CLI args.
"""
super(TorchRankerAgent, cls).add_cmdline_args(argparser)
agent = argparser.add_argument_group('TorchRankerAgent')
agent.add_argument(
'-cands',
'--candidates',
type=str,
default='inline',
choices=['batch', 'inline', 'fixed', 'batch-all-cands'],
help='The source of candidates during training '
'(see TorchRankerAgent._build_candidates() for details).',
)
agent.add_argument(
'-ecands',
'--eval-candidates',
type=str,
default='inline',
choices=['batch', 'inline', 'fixed', 'vocab', 'batch-all-cands'],
help='The source of candidates during evaluation (defaults to the same'
'value as --candidates if no flag is given)',
)
agent.add_argument(
'-icands',
'--interactive-candidates',
type=str,
default='fixed',
choices=['fixed', 'inline', 'vocab'],
help='The source of candidates during interactive mode. Since in '
'interactive mode, batchsize == 1, we cannot use batch candidates.',
)
agent.add_argument(
'--repeat-blocking-heuristic',
type='bool',
default=True,
help='Block repeating previous utterances. '
'Helpful for many models that score repeats highly, so switched '
'on by default.',
)
agent.add_argument(
'-fcp',
'--fixed-candidates-path',
type=str,
help='A text file of fixed candidates to use for all examples, one '
'candidate per line',
)
agent.add_argument(
'--fixed-candidate-vecs',
type=str,
default='reuse',
help='One of "reuse", "replace", or a path to a file with vectors '
'corresponding to the candidates at --fixed-candidates-path. '
'The default path is a /path/to/model-file.<cands_name>, where '
'<cands_name> is the name of the file (not the full path) passed by '
'the flag --fixed-candidates-path. By default, this file is created '
'once and reused. To replace it, use the "replace" option.',
)
agent.add_argument(
'--encode-candidate-vecs',
type='bool',
default=True,
help='Cache and save the encoding of the candidate vecs. This '
'might be used when interacting with the model in real time '
'or evaluating on fixed candidate set when the encoding of '
'the candidates is independent of the input.',
)
agent.add_argument(
'--encode-candidate-vecs-batchsize',
type=int,
default=256,
hidden=True,
help='Batchsize when encoding candidate vecs',
)
agent.add_argument(
'--init-model',
type=str,
default=None,
help='Initialize model with weights from this file.',
)
agent.add_argument(
'--train-predict',
type='bool',
default=False,
help='Get predictions and calculate mean rank during the train '
'step. Turning this on may slow down training.',
)
agent.add_argument(
'--cap-num-predictions',
type=int,
default=100,
help='Limit to the number of predictions in output.text_candidates',
)
agent.add_argument(
'--ignore-bad-candidates',
type='bool',
default=False,
help='Ignore examples for which the label is not present in the '
'label candidates. Default behavior results in RuntimeError. ',
)
agent.add_argument(
'--rank-top-k',
type=int,
default=-1,
help='Ranking returns the top k results of k > 0, otherwise sorts every '
'single candidate according to the ranking.',
)
agent.add_argument(
'--inference',
choices={'max', 'topk'},
default='max',
help='Final response output algorithm',
)
agent.add_argument(
'--topk',
type=int,
default=5,
help='K used in Top K sampling inference, when selected',
)
agent.add_argument(
'--return-cand-scores',
type='bool',
default=False,
help='Return sorted candidate scores from eval_step',
)
def __init__(self, opt: Opt, shared=None):
# Must call _get_init_model() first so that paths are updated if necessary
# (e.g., a .dict file)
init_model, is_finetune = self._get_init_model(opt, shared)
opt['rank_candidates'] = True
self._set_candidate_variables(opt)
super().__init__(opt, shared)
states: Dict[str, Any]
if shared:
states = {}
else:
# Note: we cannot change the type of metrics ahead of time, so you
# should correctly initialize to floats or ints here
self.criterion = self.build_criterion()
self.model = self.build_model()
if self.model is None or self.criterion is None:
raise AttributeError(
'build_model() and build_criterion() need to return the model '
'or criterion'
)
train_params = trainable_parameters(self.model)
total_params = total_parameters(self.model)
logging.info(
f"Total parameters: {total_params:,d} ({train_params:,d} trainable)"
)
if self.fp16:
self.model = self.model.half()
if init_model:
logging.info(f'Loading existing model parameters from {init_model}')
states = self.load(init_model)
else:
states = {}
if self.use_cuda:
if self.model_parallel:
self.model = PipelineHelper().make_parallel(self.model)
else:
self.model.cuda()
if self.data_parallel:
self.model = torch.nn.DataParallel(self.model)
self.criterion.cuda()
self.rank_top_k = opt.get('rank_top_k', -1)
# Set fixed and vocab candidates if applicable
self.set_fixed_candidates(shared)
self.set_vocab_candidates(shared)
if shared:
# We don't use get here because hasattr is used on optimizer later.
if 'optimizer' in shared:
self.optimizer = shared['optimizer']
elif self._should_initialize_optimizer():
# only build an optimizer if we're training
optim_params = [p for p in self.model.parameters() if p.requires_grad]
self.init_optim(
optim_params, states.get('optimizer'), states.get('optimizer_type')
)
self.build_lr_scheduler(states, hard_reset=is_finetune)
if shared is None and is_distributed():
device_ids = None if self.model_parallel else [self.opt['gpu']]
self.model = torch.nn.parallel.DistributedDataParallel(
self.model, device_ids=device_ids, broadcast_buffers=False
)
def build_criterion(self):
"""
Construct and return the loss function.
By default torch.nn.CrossEntropyLoss.
"""
if self.fp16:
return FP16SafeCrossEntropy(reduction='none')
else:
return torch.nn.CrossEntropyLoss(reduction='none')
def _set_candidate_variables(self, opt):
"""
Sets candidate variables from opt.
NOTE: we call this function prior to `super().__init__` so
that these variables are set properly during the call to the
`set_interactive_mode` function.
"""
# candidate variables
self.candidates = opt['candidates']
self.eval_candidates = opt['eval_candidates']
# options
self.fixed_candidates_path = opt['fixed_candidates_path']
self.ignore_bad_candidates = opt['ignore_bad_candidates']
self.encode_candidate_vecs = opt['encode_candidate_vecs']
def set_interactive_mode(self, mode, shared=False):
"""
Set interactive mode defaults.
In interactive mode, we set `ignore_bad_candidates` to True.
Additionally, we change the `eval_candidates` to the option
specified in `--interactive-candidates`, which defaults to False.
Interactive mode possibly changes the fixed candidates path if it
does not exist, automatically creating a candidates file from the
specified task.
"""
super().set_interactive_mode(mode, shared)
if not mode:
# Not in interactive mode, nothing to do
return
# Override eval_candidates to interactive_candidates
self.eval_candidates = self.opt.get('interactive_candidates', 'fixed')
if self.eval_candidates == 'fixed':
# Set fixed candidates path if it does not exist
if self.fixed_candidates_path is None or self.fixed_candidates_path == '':
# Attempt to get a standard candidate set for the given task
path = self.get_task_candidates_path()
if path:
if not shared:
logging.info(f'Setting fixed_candidates path to: {path}')
self.fixed_candidates_path = path
# Ignore bad candidates in interactive mode
self.ignore_bad_candidates = True
return
def get_task_candidates_path(self):
path = self.opt['model_file'] + '.cands-' + self.opt['task'] + '.cands'
if os.path.isfile(path) and self.opt['fixed_candidate_vecs'] == 'reuse':
return path
logging.warn(f'Building candidates file as they do not exist: {path}')
from parlai.scripts.build_candidates import build_cands
from copy import deepcopy
opt = deepcopy(self.opt)
opt['outfile'] = path
opt['datatype'] = 'train:evalmode'
opt['interactive_task'] = False
opt['batchsize'] = 1
build_cands(opt)
return path
@abstractmethod
def score_candidates(self, batch, cand_vecs, cand_encs=None):
"""
Given a batch and candidate set, return scores (for ranking).
:param Batch batch:
a Batch object (defined in torch_agent.py)
:param LongTensor cand_vecs:
padded and tokenized candidates
:param FloatTensor cand_encs:
encoded candidates, if these are passed into the function (in cases
where we cache the candidate encodings), you do not need to call
self.model on cand_vecs
"""
pass
def _maybe_invalidate_fixed_encs_cache(self):
if self.candidates != 'fixed':
self.fixed_candidate_encs = None
def _get_batch_train_metrics(self, scores):
"""
Get fast metrics calculations if we train with batch candidates.
Specifically, calculate accuracy ('train_accuracy'), average rank, and mean
reciprocal rank.
"""
batchsize = scores.size(0)
# get accuracy
targets = scores.new_empty(batchsize).long()
targets = torch.arange(batchsize, out=targets)
nb_ok = (scores.max(dim=1)[1] == targets).float()
self.record_local_metric('train_accuracy', AverageMetric.many(nb_ok))
# calculate mean_rank
above_dot_prods = scores - scores.diag().view(-1, 1)
ranks = (above_dot_prods > 0).float().sum(dim=1) + 1
mrr = 1.0 / (ranks + 0.00001)
self.record_local_metric('rank', AverageMetric.many(ranks))
self.record_local_metric('mrr', AverageMetric.many(mrr))
def _get_train_preds(self, scores, label_inds, cands, cand_vecs):
"""
Return predictions from training.
"""
# TODO: speed these calculations up
batchsize = scores.size(0)
if self.rank_top_k > 0:
_, ranks = scores.topk(
min(self.rank_top_k, scores.size(1)), 1, largest=True
)
else:
_, ranks = scores.sort(1, descending=True)
ranks_m = []
mrrs_m = []
for b in range(batchsize):
rank = (ranks[b] == label_inds[b]).nonzero()
rank = rank.item() if len(rank) == 1 else scores.size(1)
ranks_m.append(1 + rank)
mrrs_m.append(1.0 / (1 + rank))
self.record_local_metric('rank', AverageMetric.many(ranks_m))
self.record_local_metric('mrr', AverageMetric.many(mrrs_m))
ranks = ranks.cpu()
# Here we get the top prediction for each example, but do not
# return the full ranked list for the sake of training speed
preds = []
for i, ordering in enumerate(ranks):
if cand_vecs.dim() == 2: # num cands x max cand length
cand_list = cands
elif cand_vecs.dim() == 3: # batchsize x num cands x max cand length
cand_list = cands[i]
if len(ordering) != len(cand_list):
# We may have added padded cands to fill out the batch;
# Here we break after finding the first non-pad cand in the
# ranked list
for x in ordering:
if x < len(cand_list):
preds.append(cand_list[x])
break
else:
preds.append(cand_list[ordering[0]])
return Output(preds)
def is_valid(self, obs):
"""
Override from TorchAgent.
Check to see if label candidates contain the label.
"""
if not self.ignore_bad_candidates:
return super().is_valid(obs)
if not super().is_valid(obs):
return False
# skip examples for which the set of label candidates do not
# contain the label
if 'labels_vec' in obs and 'label_candidates_vecs' in obs:
cand_vecs = obs['label_candidates_vecs']
label_vec = obs['labels_vec']
matches = [x for x in cand_vecs if torch.equal(x, label_vec)]
if len(matches) == 0:
warn_once(
'At least one example has a set of label candidates that '
'does not contain the label.'
)
return False
return True
def train_step(self, batch):
"""
Train on a single batch of examples.
"""
self._maybe_invalidate_fixed_encs_cache()
if batch.text_vec is None and batch.image is None:
return
self.model.train()
self.zero_grad()
cands, cand_vecs, label_inds = self._build_candidates(
batch, source=self.candidates, mode='train'
)
try:
scores = self.score_candidates(batch, cand_vecs)
loss = self.criterion(scores, label_inds)
self.record_local_metric('mean_loss', AverageMetric.many(loss))
loss = loss.mean()
self.backward(loss)
self.update_params()
except RuntimeError as e:
# catch out of memory exceptions during fwd/bck (skip batch)
if 'out of memory' in str(e):
logging.error(
'Ran out of memory, skipping batch. '
'if this happens frequently, decrease batchsize or '
'truncate the inputs to the model.'
)
return Output()
else:
raise e
# Get train predictions
if self.candidates == 'batch':
self._get_batch_train_metrics(scores)
return Output()
if not self.opt.get('train_predict', False):
warn_once(
"Some training metrics are omitted for speed. Set the flag "
"`--train-predict` to calculate train metrics."
)
return Output()
return self._get_train_preds(scores, label_inds, cands, cand_vecs)
def eval_step(self, batch):
"""
Evaluate a single batch of examples.
"""
if batch.text_vec is None and batch.image is None:
return
batchsize = (
batch.text_vec.size(0)
if batch.text_vec is not None
else batch.image.size(0)
)
self.model.eval()
cands, cand_vecs, label_inds = self._build_candidates(
batch, source=self.eval_candidates, mode='eval'
)
cand_encs = None
if self.encode_candidate_vecs and self.eval_candidates in ['fixed', 'vocab']:
# if we cached candidate encodings for a fixed list of candidates,
# pass those into the score_candidates function
if self.fixed_candidate_encs is None:
self.fixed_candidate_encs = self._make_candidate_encs(
cand_vecs
).detach()
if self.eval_candidates == 'fixed':
cand_encs = self.fixed_candidate_encs
elif self.eval_candidates == 'vocab':
cand_encs = self.vocab_candidate_encs
scores = self.score_candidates(batch, cand_vecs, cand_encs=cand_encs)
if self.rank_top_k > 0:
sorted_scores, ranks = scores.topk(
min(self.rank_top_k, scores.size(1)), 1, largest=True
)
else:
sorted_scores, ranks = scores.sort(1, descending=True)
if self.opt.get('return_cand_scores', False):
sorted_scores = sorted_scores.cpu()
else:
sorted_scores = None
# Update metrics
if label_inds is not None:
loss = self.criterion(scores, label_inds)
self.record_local_metric('loss', AverageMetric.many(loss))
ranks_m = []
mrrs_m = []
for b in range(batchsize):
rank = (ranks[b] == label_inds[b]).nonzero()
rank = rank.item() if len(rank) == 1 else scores.size(1)
ranks_m.append(1 + rank)
mrrs_m.append(1.0 / (1 + rank))
self.record_local_metric('rank', AverageMetric.many(ranks_m))
self.record_local_metric('mrr', AverageMetric.many(mrrs_m))
ranks = ranks.cpu()
max_preds = self.opt['cap_num_predictions']
cand_preds = []
for i, ordering in enumerate(ranks):
if cand_vecs.dim() == 2:
cand_list = cands
elif cand_vecs.dim() == 3:
cand_list = cands[i]
# using a generator instead of a list comprehension allows
# to cap the number of elements.
cand_preds_generator = (
cand_list[rank] for rank in ordering if rank < len(cand_list)
)
cand_preds.append(list(islice(cand_preds_generator, max_preds)))
if (
self.opt.get('repeat_blocking_heuristic', True)
and self.eval_candidates == 'fixed'
):
cand_preds = self.block_repeats(cand_preds)
if self.opt.get('inference', 'max') == 'max':
preds = [cand_preds[i][0] for i in range(batchsize)]
else:
# Top-k inference.
preds = []
for i in range(batchsize):
preds.append(random.choice(cand_preds[i][0 : self.opt['topk']]))
return Output(preds, cand_preds, sorted_scores=sorted_scores)
def block_repeats(self, cand_preds):
"""
Heuristic to block a model repeating a line from the history.
"""
history_strings = []
for h in self.history.history_raw_strings:
# Heuristic: Block any given line in the history, splitting by '\n'.
history_strings.extend(h.split('\n'))
new_preds = []
for cp in cand_preds:
np = []
for c in cp:
if c not in history_strings:
np.append(c)
new_preds.append(np)
return new_preds
def _set_label_cands_vec(self, *args, **kwargs):
"""
Set the 'label_candidates_vec' field in the observation.
Useful to override to change vectorization behavior.
"""
obs = args[0]
if 'labels' in obs:
cands_key = 'candidates'
else:
cands_key = 'eval_candidates'
if self.opt[cands_key] not in ['inline', 'batch-all-cands']:
# vectorize label candidates if and only if we are using inline
# candidates
return obs
return super()._set_label_cands_vec(*args, **kwargs)
def _build_candidates(self, batch, source, mode):
"""
Build a candidate set for this batch.
:param batch:
a Batch object (defined in torch_agent.py)
:param source:
the source from which candidates should be built, one of
['batch', 'batch-all-cands', 'inline', 'fixed']
:param mode:
'train' or 'eval'
:return: tuple of tensors (label_inds, cands, cand_vecs)
label_inds: A [bsz] LongTensor of the indices of the labels for each
example from its respective candidate set
cands: A [num_cands] list of (text) candidates
OR a [batchsize] list of such lists if source=='inline'
cand_vecs: A padded [num_cands, seqlen] LongTensor of vectorized candidates
OR a [batchsize, num_cands, seqlen] LongTensor if source=='inline'
Possible sources of candidates:
* batch: the set of all labels in this batch
Use all labels in the batch as the candidate set (with all but the
example's label being treated as negatives).
Note: with this setting, the candidate set is identical for all
examples in a batch. This option may be undesirable if it is possible
for duplicate labels to occur in a batch, since the second instance of
the correct label will be treated as a negative.
* batch-all-cands: the set of all candidates in this batch
Use all candidates in the batch as candidate set.
Note 1: This can result in a very large number of candidates.
Note 2: In this case we will deduplicate candidates.
Note 3: just like with 'batch' the candidate set is identical
for all examples in a batch.
* inline: batch_size lists, one list per example
If each example comes with a list of possible candidates, use those.
Note: With this setting, each example will have its own candidate set.
* fixed: one global candidate list, provided in a file from the user
If self.fixed_candidates is not None, use a set of fixed candidates for
all examples.
Note: this setting is not recommended for training unless the
universe of possible candidates is very small.
* vocab: one global candidate list, extracted from the vocabulary with the
exception of self.NULL_IDX.
"""
label_vecs = batch.label_vec # [bsz] list of lists of LongTensors
label_inds = None
batchsize = (
batch.text_vec.size(0)
if batch.text_vec is not None
else batch.image.size(0)
)
if label_vecs is not None:
assert label_vecs.dim() == 2
if source == 'batch':
warn_once(
'[ Executing {} mode with batch labels as set of candidates. ]'
''.format(mode)
)
if batchsize == 1:
warn_once(
"[ Warning: using candidate source 'batch' and observed a "
"batch of size 1. This may be due to uneven batch sizes at "
"the end of an epoch. ]"
)
if label_vecs is None:
raise ValueError(
"If using candidate source 'batch', then batch.label_vec cannot be "
"None."
)
cands = batch.labels
cand_vecs = label_vecs
label_inds = label_vecs.new_tensor(range(batchsize))
elif source == 'batch-all-cands':
warn_once(
'[ Executing {} mode with all candidates provided in the batch ]'
''.format(mode)
)
if batch.candidate_vecs is None:
raise ValueError(
"If using candidate source 'batch-all-cands', then batch."
"candidate_vecs cannot be None. If your task does not have "
"inline candidates, consider using one of "
"--{m}={{'batch','fixed','vocab'}}."
"".format(m='candidates' if mode == 'train' else 'eval-candidates')
)
# initialize the list of cands with the labels
cands = []
all_cands_vecs = []
# dictionary used for deduplication
cands_to_id = {}
for i, cands_for_sample in enumerate(batch.candidates):
for j, cand in enumerate(cands_for_sample):
if cand not in cands_to_id:
cands.append(cand)
cands_to_id[cand] = len(cands_to_id)
all_cands_vecs.append(batch.candidate_vecs[i][j])
cand_vecs, _ = self._pad_tensor(all_cands_vecs)
label_inds = label_vecs.new_tensor(
[cands_to_id[label] for label in batch.labels]
)
elif source == 'inline':
warn_once(
'[ Executing {} mode with provided inline set of candidates ]'
''.format(mode)
)
if batch.candidate_vecs is None:
raise ValueError(
"If using candidate source 'inline', then batch.candidate_vecs "
"cannot be None. If your task does not have inline candidates, "
"consider using one of --{m}={{'batch','fixed','vocab'}}."
"".format(m='candidates' if mode == 'train' else 'eval-candidates')
)
cands = batch.candidates
cand_vecs = padded_3d(
batch.candidate_vecs,
self.NULL_IDX,
use_cuda=self.use_cuda,
fp16friendly=self.fp16,
)
if label_vecs is not None:
label_inds = label_vecs.new_empty((batchsize))
bad_batch = False
for i, label_vec in enumerate(label_vecs):
label_vec_pad = label_vec.new_zeros(cand_vecs[i].size(1)).fill_(
self.NULL_IDX
)
if cand_vecs[i].size(1) < len(label_vec):
label_vec = label_vec[0 : cand_vecs[i].size(1)]
label_vec_pad[0 : label_vec.size(0)] = label_vec
label_inds[i] = self._find_match(cand_vecs[i], label_vec_pad)
if label_inds[i] == -1:
bad_batch = True
if bad_batch:
if self.ignore_bad_candidates and not self.is_training:
label_inds = None
else:
raise RuntimeError(
'At least one of your examples has a set of label candidates '
'that does not contain the label. To ignore this error '
'set `--ignore-bad-candidates True`.'
)
elif source == 'fixed':
if self.fixed_candidates is None:
raise ValueError(
"If using candidate source 'fixed', then you must provide the path "
"to a file of candidates with the flag --fixed-candidates-path or "
"the name of a task with --fixed-candidates-task."
)
warn_once(
"[ Executing {} mode with a common set of fixed candidates "
"(n = {}). ]".format(mode, len(self.fixed_candidates))
)
cands = self.fixed_candidates
cand_vecs = self.fixed_candidate_vecs
if label_vecs is not None:
label_inds = label_vecs.new_empty((batchsize))
bad_batch = False
for batch_idx, label_vec in enumerate(label_vecs):
max_c_len = cand_vecs.size(1)
label_vec_pad = label_vec.new_zeros(max_c_len).fill_(self.NULL_IDX)
if max_c_len < len(label_vec):
label_vec = label_vec[0:max_c_len]
label_vec_pad[0 : label_vec.size(0)] = label_vec
label_inds[batch_idx] = self._find_match(cand_vecs, label_vec_pad)
if label_inds[batch_idx] == -1:
bad_batch = True
if bad_batch:
if self.ignore_bad_candidates and not self.is_training:
label_inds = None
else:
raise RuntimeError(
'At least one of your examples has a set of label candidates '
'that does not contain the label. To ignore this error '
'set `--ignore-bad-candidates True`.'
)
elif source == 'vocab':
warn_once(
'[ Executing {} mode with tokens from vocabulary as candidates. ]'
''.format(mode)
)
cands = self.vocab_candidates
cand_vecs = self.vocab_candidate_vecs
# NOTE: label_inds is None here, as we will not find the label in
# the set of vocab candidates
else:
raise Exception("Unrecognized source: %s" % source)
return (cands, cand_vecs, label_inds)
@staticmethod
def _find_match(cand_vecs, label_vec):
matches = ((cand_vecs == label_vec).sum(1) == cand_vecs.size(1)).nonzero()
if len(matches) > 0:
return matches[0]
return -1
def share(self):
"""
Share model parameters.
"""
shared = super().share()
shared['fixed_candidates'] = self.fixed_candidates
shared['fixed_candidate_vecs'] = self.fixed_candidate_vecs
shared['fixed_candidate_encs'] = self.fixed_candidate_encs
shared['num_fixed_candidates'] = self.num_fixed_candidates
shared['vocab_candidates'] = self.vocab_candidates
shared['vocab_candidate_vecs'] = self.vocab_candidate_vecs
shared['vocab_candidate_encs'] = self.vocab_candidate_encs
if hasattr(self, 'optimizer'):
shared['optimizer'] = self.optimizer
return shared
def set_vocab_candidates(self, shared):
"""
Load the tokens from the vocab as candidates.
self.vocab_candidates will contain a [num_cands] list of strings
self.vocab_candidate_vecs will contain a [num_cands, 1] LongTensor
"""
if shared:
self.vocab_candidates = shared['vocab_candidates']
self.vocab_candidate_vecs = shared['vocab_candidate_vecs']
self.vocab_candidate_encs = shared['vocab_candidate_encs']
else:
if 'vocab' in (self.opt['candidates'], self.opt['eval_candidates']):
cands = []
vecs = []
for ind in range(1, len(self.dict)):
cands.append(self.dict.ind2tok[ind])
vecs.append(ind)
self.vocab_candidates = cands
self.vocab_candidate_vecs = torch.LongTensor(vecs).unsqueeze(1)
logging.info(
"Loaded fixed candidate set (n = {}) from vocabulary"
"".format(len(self.vocab_candidates))
)
if self.use_cuda:
self.vocab_candidate_vecs = self.vocab_candidate_vecs.cuda()
if self.encode_candidate_vecs:
# encode vocab candidate vecs
self.vocab_candidate_encs = self._make_candidate_encs(
self.vocab_candidate_vecs
)
if self.use_cuda:
self.vocab_candidate_encs = self.vocab_candidate_encs.cuda()
if self.fp16:
self.vocab_candidate_encs = self.vocab_candidate_encs.half()
else:
self.vocab_candidate_encs = self.vocab_candidate_encs.float()
else:
self.vocab_candidate_encs = None
else:
self.vocab_candidates = None
self.vocab_candidate_vecs = None
self.vocab_candidate_encs = None
def set_fixed_candidates(self, shared):
"""
Load a set of fixed candidates and their vectors (or vectorize them here).
self.fixed_candidates will contain a [num_cands] list of strings
self.fixed_candidate_vecs will contain a [num_cands, seq_len] LongTensor
See the note on the --fixed-candidate-vecs flag for an explanation of the
'reuse', 'replace', or path options.
Note: TorchRankerAgent by default converts candidates to vectors by vectorizing
in the common sense (i.e., replacing each token with its index in the
dictionary). If a child model wants to additionally perform encoding, it can
overwrite the vectorize_fixed_candidates() method to produce encoded vectors
instead of just vectorized ones.
"""
if shared:
self.fixed_candidates = shared['fixed_candidates']
self.fixed_candidate_vecs = shared['fixed_candidate_vecs']
self.fixed_candidate_encs = shared['fixed_candidate_encs']
self.num_fixed_candidates = shared['num_fixed_candidates']
else:
self.num_fixed_candidates = 0
opt = self.opt
cand_path = self.fixed_candidates_path
if 'fixed' in (self.candidates, self.eval_candidates):
if not cand_path:
# Attempt to get a standard candidate set for the given task
path = self.get_task_candidates_path()
if path:
logging.info(f"setting fixed_candidates path to: {path}")
self.fixed_candidates_path = path
cand_path = self.fixed_candidates_path
# Load candidates
logging.info(f"Loading fixed candidate set from {cand_path}")
with open(cand_path, 'r', encoding='utf-8') as f:
cands = [line.strip() for line in f.readlines()]
# Load or create candidate vectors
if os.path.isfile(self.opt['fixed_candidate_vecs']):
vecs_path = opt['fixed_candidate_vecs']
vecs = self.load_candidates(vecs_path)
else:
setting = self.opt['fixed_candidate_vecs']
model_dir, model_file = os.path.split(self.opt['model_file'])
model_name = os.path.splitext(model_file)[0]
cands_name = os.path.splitext(os.path.basename(cand_path))[0]
vecs_path = os.path.join(
model_dir, '.'.join([model_name, cands_name, 'vecs'])
)
if setting == 'reuse' and os.path.isfile(vecs_path):
vecs = self.load_candidates(vecs_path)
else: # setting == 'replace' OR generating for the first time
vecs = self._make_candidate_vecs(cands)
self._save_candidates(vecs, vecs_path)
self.fixed_candidates = cands
self.num_fixed_candidates = len(self.fixed_candidates)
self.fixed_candidate_vecs = vecs
if self.use_cuda:
self.fixed_candidate_vecs = self.fixed_candidate_vecs.cuda()
if self.encode_candidate_vecs:
# candidate encodings are fixed so set them up now
enc_path = os.path.join(
model_dir, '.'.join([model_name, cands_name, 'encs'])
)
if setting == 'reuse' and os.path.isfile(enc_path):
encs = self.load_candidates(enc_path, cand_type='encodings')
else:
encs = self._make_candidate_encs(self.fixed_candidate_vecs)
self._save_candidates(
encs, path=enc_path, cand_type='encodings'
)
self.fixed_candidate_encs = encs
if self.use_cuda:
self.fixed_candidate_encs = self.fixed_candidate_encs.cuda()
if self.fp16:
self.fixed_candidate_encs = self.fixed_candidate_encs.half()
else:
self.fixed_candidate_encs = self.fixed_candidate_encs.float()
else:
self.fixed_candidate_encs = None
else:
self.fixed_candidates = None
self.fixed_candidate_vecs = None
self.fixed_candidate_encs = None
def load_candidates(self, path, cand_type='vectors'):
"""
Load fixed candidates from a path.
"""
logging.info(f"Loading fixed candidate set {cand_type} from {path}")
return torch.load(path, map_location=lambda cpu, _: cpu)
def _make_candidate_vecs(self, cands):
"""
Prebuild cached vectors for fixed candidates.
"""
cand_batches = [cands[i : i + 512] for i in range(0, len(cands), 512)]
logging.info(
f"Vectorizing fixed candidate set ({len(cand_batches)} batch(es) of up to 512)"
)
cand_vecs = []
for batch in tqdm(cand_batches):
cand_vecs.extend(self.vectorize_fixed_candidates(batch))
return padded_3d(
[cand_vecs], pad_idx=self.NULL_IDX, dtype=cand_vecs[0].dtype
).squeeze(0)
def _save_candidates(self, vecs, path, cand_type='vectors'):
"""
Save cached vectors.
"""
logging.info(f"Saving fixed candidate set {cand_type} to {path}")
with open(path, 'wb') as f:
torch.save(vecs, f)
def encode_candidates(self, padded_cands):
"""
Convert the given candidates to vectors.
This is an abstract method that must be implemented by the user.
:param padded_cands:
The padded candidates.
"""
raise NotImplementedError(
'Abstract method: user must implement encode_candidates(). '
'If your agent encodes candidates independently '
'from context, you can get performance gains with fixed cands by '
'implementing this function and running with the flag '
'--encode-candidate-vecs True.'
)
def _make_candidate_encs(self, vecs):
"""
Encode candidates from candidate vectors.
Requires encode_candidates() to be implemented.
"""
cand_encs = []
bsz = self.opt.get('encode_candidate_vecs_batchsize', 256)
vec_batches = [vecs[i : i + bsz] for i in range(0, len(vecs), bsz)]
logging.info(
"Encoding fixed candidates set from ({} batch(es) of up to {}) ]"
"".format(len(vec_batches), bsz)
)
# Put model into eval mode when encoding candidates
self.model.eval()
with torch.no_grad():
for vec_batch in tqdm(vec_batches):
cand_encs.append(self.encode_candidates(vec_batch).cpu())
return torch.cat(cand_encs, 0).to(vec_batch.device)
def vectorize_fixed_candidates(self, cands_batch, add_start=False, add_end=False):
"""
Convert a batch of candidates from text to vectors.
:param cands_batch:
a [batchsize] list of candidates (strings)
:returns:
a [num_cands] list of candidate vectors
By default, candidates are simply vectorized (tokens replaced by token ids).
A child class may choose to overwrite this method to perform vectorization as
well as encoding if so desired.
"""
return [
self._vectorize_text(
cand,
truncate=self.label_truncate,
truncate_left=False,
add_start=add_start,
add_end=add_end,
)
for cand in cands_batch
]
class TorchClassifierAgent(TorchAgent):
"""
Abstract Classifier agent. Only meant to be extended.
TorchClassifierAgent aims to handle much of the bookkeeping any classification
model.
"""
@staticmethod
def add_cmdline_args(parser):
"""
Add CLI args.
"""
TorchAgent.add_cmdline_args(parser)
parser = parser.add_argument_group('Torch Classifier Arguments')
# class arguments
parser.add_argument(
'--classes',
type=str,
nargs='*',
default=None,
help='the name of the classes.',
)
parser.add_argument(
'--class-weights',
type=float,
nargs='*',
default=None,
help='weight of each of the classes for the softmax',
)
parser.add_argument(
'--ref-class',
type=str,
default=None,
hidden=True,
help='the class that will be used to compute '
'precision and recall. By default the first '
'class.',
)
parser.add_argument(
'--threshold',
type=float,
default=0.5,
help='during evaluation, threshold for choosing '
'ref class; only applies to binary '
'classification',
)
# interactive mode
parser.add_argument(
'--print-scores',
type='bool',
default=False,
help='print probability of chosen class during ' 'interactive mode',
)
# miscellaneous arguments
parser.add_argument(
'--data-parallel',
type='bool',
default=False,
help='uses nn.DataParallel for multi GPU',
)
parser.add_argument(
'--classes-from-file',
type=str,
default=None,
help='loads the list of classes from a file',
)
parser.add_argument(
'--ignore-labels',
type='bool',
default=None,
help='Ignore labels provided to model',
)
def __init__(self, opt: Opt, shared=None):
init_model, self.is_finetune = self._get_init_model(opt, shared)
super().__init__(opt, shared)
# set up classes
if opt.get('classes') is None and opt.get('classes_from_file') is None:
raise RuntimeError(
'Must specify --classes or --classes-from-file argument.'
)
if not shared:
if opt['classes_from_file'] is not None:
with open(opt['classes_from_file']) as f:
self.class_list = f.read().splitlines()
else:
self.class_list = opt['classes']
self.class_dict = {val: i for i, val in enumerate(self.class_list)}
if opt.get('class_weights', None) is not None:
self.class_weights = opt['class_weights']
else:
self.class_weights = [1.0 for c in self.class_list]
self.reset_metrics()
else:
self.class_list = shared['class_list']
self.class_dict = shared['class_dict']
self.class_weights = shared['class_weights']
# in binary classfication, opt['threshold'] applies to ref class
if opt['ref_class'] is None or opt['ref_class'] not in self.class_dict:
self.ref_class = self.class_list[0]
else:
self.ref_class = opt['ref_class']
ref_class_id = self.class_list.index(self.ref_class)
if ref_class_id != 0:
# move to the front of the class list
self.class_list.insert(0, self.class_list.pop(ref_class_id))
# set up threshold, only used in binary classification
if len(self.class_list) == 2 and opt.get('threshold', 0.5) != 0.5:
self.threshold = opt['threshold']
else:
self.threshold = None
# set up model and optimizers
if shared:
self.model = shared['model']
else:
self.model = self.build_model()
self.criterion = self.build_criterion()
if self.model is None or self.criterion is None:
raise AttributeError(
'build_model() and build_criterion() need to return the model or criterion'
)
if init_model:
logging.info(f'Loading existing model parameters from {init_model}')
self.load(init_model)
if self.use_cuda:
if self.model_parallel:
self.model = PipelineHelper().make_parallel(self.model)
else:
self.model.cuda()
if self.data_parallel:
self.model = torch.nn.DataParallel(self.model)
self.criterion.cuda()
if shared:
# We don't use get here because hasattr is used on optimizer later.
if 'optimizer' in shared:
self.optimizer = shared['optimizer']
elif self._should_initialize_optimizer():
optim_params = [p for p in self.model.parameters() if p.requires_grad]
self.init_optim(optim_params)
self.build_lr_scheduler()
def build_criterion(self):
weight_tensor = torch.FloatTensor(self.class_weights)
return torch.nn.CrossEntropyLoss(weight=weight_tensor, reduction='none')
def share(self):
"""
Share model parameters.
"""
shared = super().share()
shared['class_dict'] = self.class_dict
shared['class_list'] = self.class_list
shared['class_weights'] = self.class_weights
shared['model'] = self.model
if hasattr(self, 'optimizer'):
shared['optimizer'] = self.optimizer
return shared
def _get_labels(self, batch):
"""
Obtain the correct labels.
Raises a ``KeyError`` if one of the labels is not in the class list.
"""
try:
labels_indices_list = [self.class_dict[label] for label in batch.labels]
except KeyError as e:
warn_once('One of your labels is not in the class list.')
raise e
labels_tensor = torch.LongTensor(labels_indices_list)
if self.use_cuda:
labels_tensor = labels_tensor.cuda()
return labels_tensor
def _update_confusion_matrix(self, batch, predictions):
"""
Update the confusion matrix given the batch and predictions.
:param predictions:
(list of string of length batchsize) label predicted by the
classifier
:param batch:
a Batch object (defined in torch_agent.py)
"""
f1_dict = {}
for class_name in self.class_list:
prec_str = f'class_{class_name}_prec'
recall_str = f'class_{class_name}_recall'
f1_str = f'class_{class_name}_f1'
precision, recall, f1 = ConfusionMatrixMetric.compute_metrics(
predictions, batch.labels, class_name
)
f1_dict[class_name] = f1
self.record_local_metric(prec_str, precision)
self.record_local_metric(recall_str, recall)
self.record_local_metric(f1_str, f1)
self.record_local_metric('weighted_f1', WeightedF1Metric.compute_many(f1_dict))
def _format_interactive_output(self, probs, prediction_id):
"""
Format interactive mode output with scores.
"""
preds = []
for i, pred_id in enumerate(prediction_id.tolist()):
prob = round_sigfigs(probs[i][pred_id], 4)
preds.append(
'Predicted class: {}\nwith probability: {}'.format(
self.class_list[pred_id], prob
)
)
return preds
def train_step(self, batch):
"""
Train on a single batch of examples.
"""
if batch.text_vec is None:
return Output()
self.model.train()
self.optimizer.zero_grad()
# calculate loss
labels = self._get_labels(batch)
scores = self.score(batch)
loss = self.criterion(scores, labels)
self.record_local_metric('loss', AverageMetric.many(loss))
loss = loss.mean()
loss.backward()
self.update_params()
# get predictions
_, prediction_id = torch.max(scores.cpu(), 1)
preds = [self.class_list[idx] for idx in prediction_id]
self._update_confusion_matrix(batch, preds)
return Output(preds)
def eval_step(self, batch):
"""
Train on a single batch of examples.
"""
if batch.text_vec is None:
return
self.model.eval()
scores = self.score(batch)
probs = F.softmax(scores, dim=1)
if self.threshold is None:
_, prediction_id = torch.max(probs.cpu(), 1)
else:
ref_prob = probs.cpu()[:, 0]
# choose ref class if Prob(ref class) > threshold
prediction_id = (ref_prob <= self.threshold).to(torch.int64)
preds = [self.class_list[idx] for idx in prediction_id]
if batch.labels is None or self.opt['ignore_labels']:
# interactive mode
if self.opt.get('print_scores', False):
preds = self._format_interactive_output(probs, prediction_id)
else:
labels = self._get_labels(batch)
loss = self.criterion(scores, labels)
self.record_local_metric('loss', AverageMetric.many(loss))
loss = loss.mean()
self._update_confusion_matrix(batch, preds)
if self.opt.get('print_scores', False):
return Output(preds, probs=probs.cpu())
else:
return Output(preds)
def score(self, batch):
"""
Given a batch and labels, returns the scores.
:param batch:
a Batch object (defined in torch_agent.py)
:return:
a [bsz, num_classes] FloatTensor containing the score of each
class.
"""
raise NotImplementedError('Abstract class: user must implement score()')
class TorchClassifierAgent(TorchAgent):
"""
Abstract Classifier agent. Only meant to be extended.
TorchClassifierAgent aims to handle much of the bookkeeping any classification
model.
"""
@staticmethod
def add_cmdline_args(parser):
"""
Add CLI args.
"""
TorchAgent.add_cmdline_args(parser)
parser = parser.add_argument_group('Torch Classifier Arguments')
# class arguments
parser.add_argument(
'--classes',
type=str,
nargs='*',
default=None,
help='the name of the classes.',
)
parser.add_argument(
'--class-weights',
type=float,
nargs='*',
default=None,
help='weight of each of the classes for the softmax',
)
parser.add_argument(
'--ref-class',
type=str,
default=None,
hidden=True,
help='the class that will be used to compute '
'precision and recall. By default the first '
'class.',
)
parser.add_argument(
'--threshold',
type=float,
default=0.5,
help='during evaluation, threshold for choosing '
'ref class; only applies to binary '
'classification',
)
# interactive mode
parser.add_argument(
'--print-scores',
type='bool',
default=False,
help='print probability of chosen class during '
'interactive mode',
)
# miscellaneous arguments
parser.add_argument(
'--data-parallel',
type='bool',
default=False,
help='uses nn.DataParallel for multi GPU',
)
parser.add_argument(
'--get-all-metrics',
type='bool',
default=True,
help='give prec/recall metrics for all classes',
)
parser.add_argument(
'--classes-from-file',
type=str,
default=None,
help='loads the list of classes from a file',
)
parser.add_argument(
'--ignore-labels',
type='bool',
default=None,
help='Ignore labels provided to model',
)
def __init__(self, opt: Opt, shared=None):
init_model, self.is_finetune = self._get_init_model(opt, shared)
super().__init__(opt, shared)
# set up classes
if opt.get('classes') is None and opt.get('classes_from_file') is None:
raise RuntimeError(
'Must specify --classes or --classes-from-file argument.')
if not shared:
if opt['classes_from_file'] is not None:
with open(opt['classes_from_file']) as f:
self.class_list = f.read().splitlines()
else:
self.class_list = opt['classes']
self.class_dict = {val: i for i, val in enumerate(self.class_list)}
if opt.get('class_weights', None) is not None:
self.class_weights = opt['class_weights']
else:
self.class_weights = [1.0 for c in self.class_list]
self.reset_metrics()
else:
self.class_list = shared['class_list']
self.class_dict = shared['class_dict']
self.class_weights = shared['class_weights']
# get reference class; if opt['get_all_metrics'] is False, this is
# used to compute metrics
# in binary classfication, opt['threshold'] applies to ref class
if opt['ref_class'] is None or opt['ref_class'] not in self.class_dict:
self.ref_class = self.class_list[0]
else:
self.ref_class = opt['ref_class']
ref_class_id = self.class_list.index(self.ref_class)
if ref_class_id != 0:
# move to the front of the class list
self.class_list.insert(0, self.class_list.pop(ref_class_id))
if not opt['get_all_metrics']:
warn_once('Using %s as the class for computing P, R, and F1' %
self.ref_class)
# set up threshold, only used in binary classification
if len(self.class_list) == 2 and opt.get('threshold', 0.5) != 0.5:
self.threshold = opt['threshold']
else:
self.threshold = None
# set up model and optimizers
if shared:
self.model = shared['model']
else:
self.model = self.build_model()
self.criterion = self.build_criterion()
if self.model is None or self.criterion is None:
raise AttributeError(
'build_model() and build_criterion() need to return the model or criterion'
)
if init_model:
print('Loading existing model parameters from ' + init_model)
self.load(init_model)
if self.use_cuda:
self.model.cuda()
if self.data_parallel:
self.model = torch.nn.DataParallel(self.model)
elif self.model_parallel:
self.model = PipelineHelper().make_parallel(self.model)
self.criterion.cuda()
if shared:
# We don't use get here because hasattr is used on optimizer later.
if 'optimizer' in shared:
self.optimizer = shared['optimizer']
else:
optim_params = [
p for p in self.model.parameters() if p.requires_grad
]
self.init_optim(optim_params)
self.build_lr_scheduler()
def build_criterion(self):
weight_tensor = torch.FloatTensor(self.class_weights)
return torch.nn.CrossEntropyLoss(weight=weight_tensor,
reduction='none')
def share(self):
"""
Share model parameters.
"""
shared = super().share()
shared['class_dict'] = self.class_dict
shared['class_list'] = self.class_list
shared['class_weights'] = self.class_weights
shared['model'] = self.model
shared['optimizer'] = self.optimizer
return shared
def _get_labels(self, batch):
"""
Obtain the correct labels.
Raises a ``KeyError`` if one of the labels is not in the class list.
"""
try:
labels_indices_list = [
self.class_dict[label] for label in batch.labels
]
except KeyError as e:
warn_once('One of your labels is not in the class list.')
raise e
labels_tensor = torch.LongTensor(labels_indices_list)
if self.use_cuda:
labels_tensor = labels_tensor.cuda()
return labels_tensor
def _update_confusion_matrix(self, batch, predictions):
"""
Update the confusion matrix given the batch and predictions.
:param batch:
a Batch object (defined in torch_agent.py)
:param predictions:
(list of string of length batchsize) label predicted by the
classifier
"""
for i, pred in enumerate(predictions):
label = batch.labels[i]
self.metrics['confusion_matrix'][(label, pred)] += 1
def _format_interactive_output(self, probs, prediction_id):
"""
Format interactive mode output with scores.
"""
preds = []
for i, pred_id in enumerate(prediction_id.tolist()):
prob = round_sigfigs(probs[i][pred_id], 4)
preds.append('Predicted class: {}\nwith probability: {}'.format(
self.class_list[pred_id], prob))
return preds
def train_step(self, batch):
"""
Train on a single batch of examples.
"""
if batch.text_vec is None:
return Output()
self.model.train()
self.optimizer.zero_grad()
# calculate loss
labels = self._get_labels(batch)
scores = self.score(batch)
loss = self.criterion(scores, labels)
self.record_local_metric('loss', AverageMetric.many(loss))
loss = loss.mean()
loss.backward()
self.update_params()
# get predictions
_, prediction_id = torch.max(scores.cpu(), 1)
preds = [self.class_list[idx] for idx in prediction_id]
self._update_confusion_matrix(batch, preds)
return Output(preds)
def eval_step(self, batch):
"""
Train on a single batch of examples.
"""
if batch.text_vec is None:
return
self.model.eval()
scores = self.score(batch)
probs = F.softmax(scores, dim=1)
if self.threshold is None:
_, prediction_id = torch.max(probs.cpu(), 1)
else:
ref_prob = probs.cpu()[:, 0]
# choose ref class if Prob(ref class) > threshold
prediction_id = ref_prob <= self.threshold
preds = [self.class_list[idx] for idx in prediction_id]
if batch.labels is None or self.opt['ignore_labels']:
# interactive mode
if self.opt.get('print_scores', False):
preds = self._format_interactive_output(probs, prediction_id)
else:
labels = self._get_labels(batch)
loss = self.criterion(scores, labels)
self.record_local_metric('loss', AverageMetric.many(loss))
loss = loss.mean()
self._update_confusion_matrix(batch, preds)
if self.opt.get('print_scores', False):
return Output(preds, probs=probs.cpu())
else:
return Output(preds)
def reset_metrics(self):
"""
Reset metrics.
"""
super().reset_metrics()
self.metrics['confusion_matrix'] = defaultdict(int)
def _report_prec_recall_metrics(self, confmat, class_name, metrics):
"""
Use the confusion matrix to compute precision and recall.
:param confmat:
the confusion matrics
:param str class_name:
the class name to compute P/R for
:param metrics:
metrics dictionary to modify
:return:
the number of examples of each class.
"""
# TODO: document these parameter types.
eps = 0.00001 # prevent divide by zero errors
true_positives = confmat[(class_name, class_name)]
num_actual_positives = (
sum([confmat[(class_name, c)] for c in self.class_list]) + eps)
num_predicted_positives = (
sum([confmat[(c, class_name)] for c in self.class_list]) + eps)
recall_str = 'class_{}_recall'.format(class_name)
prec_str = 'class_{}_prec'.format(class_name)
f1_str = 'class_{}_f1'.format(class_name)
# update metrics dict
metrics[recall_str] = true_positives / num_actual_positives
metrics[prec_str] = true_positives / num_predicted_positives
metrics[f1_str] = 2 * ((metrics[recall_str] * metrics[prec_str]) /
(metrics[recall_str] + metrics[prec_str] + eps))
return num_actual_positives
def report(self):
"""
Report loss as well as precision, recall, and F1 metrics.
"""
m = super().report()
# TODO: upgrade the confusion matrix to newer metrics
# get prec/recall metrics
confmat = self.metrics['confusion_matrix']
if self.opt.get('get_all_metrics'):
metrics_list = self.class_list
else:
# only give prec/recall metrics for ref class
metrics_list = [self.ref_class]
examples_per_class = []
for class_i in metrics_list:
class_total = self._report_prec_recall_metrics(confmat, class_i, m)
examples_per_class.append(class_total)
if len(examples_per_class) > 1:
# get weighted f1
f1 = 0
total_exs = sum(examples_per_class)
for i in range(len(self.class_list)):
f1 += (examples_per_class[i] /
total_exs) * m['class_{}_f1'.format(self.class_list[i])]
m['weighted_f1'] = f1
# get weighted accuracy
wacc = 0
for i in range(len(self.class_list)):
wacc += (1.0 / len(self.class_list)
) * m['class_{}_recall'.format(self.class_list[i])]
m['weighted_acc'] = wacc
return m
def score(self, batch):
"""
Given a batch and labels, returns the scores.
:param batch:
a Batch object (defined in torch_agent.py)
:return:
a [bsz, num_classes] FloatTensor containing the score of each
class.
"""
raise NotImplementedError(
'Abstract class: user must implement score()')
