refactor ctc, add ctc align, refactor ckpt, add warmup lr scheduler, cmvn utils

.notebook/jit_infer.ipynb

@@ -509,7 +509,7 @@
     "        print(audio_len.shape)\n",
     "        \n",
     "        #eouts, eouts_len = model.encoder(audio, audio_len)\n",
-    "        #probs = model.decoder.probs(eouts)\n",
+    "        #probs = model.decoder.softmax(eouts)\n",
     "        probs = model.forward(audio, audio_len)\n",
     "        print('paddle:', probs.numpy())\n",
     "        \n",
@@ -666,4 +666,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}
\ No newline at end of file

deepspeech/exps/deepspeech2/bin/tune.py

@@ -109,7 +109,7 @@ def tune(config, args):
 
         # model infer
         eouts, eouts_len = model.encoder(audio, audio_len)
-        probs = model.decoder.probs(eouts)
+        probs = model.decoder.softmax(eouts)
 
         # grid search
         for index, (alpha, beta) in enumerate(params_grid):

deepspeech/models/deepspeech2.py

@@ -203,7 +203,7 @@ class DeepSpeech2Model(nn.Layer):
             decoding_method=decoding_method)
 
         eouts, eouts_len = self.encoder(audio, audio_len)
-        probs = self.decoder.probs(eouts)
+        probs = self.decoder.softmax(eouts)
         return self.decoder.decode_probs(
             probs.numpy(), eouts_len, vocab_list, decoding_method,
             lang_model_path, beam_alpha, beam_beta, beam_size, cutoff_prob,
@@ -234,7 +234,9 @@ class DeepSpeech2Model(nn.Layer):
                     rnn_size=config.model.rnn_layer_size,
                     use_gru=config.model.use_gru,
                     share_rnn_weights=config.model.share_rnn_weights)
-        checkpoint.load_parameters(model, checkpoint_path=checkpoint_path)
+        infos = checkpoint.load_parameters(
+            model, checkpoint_path=checkpoint_path)
+        logger.info(f"checkpoint info: {infos}")
         layer_tools.summary(model)
         return model
 
@@ -268,5 +270,5 @@ class DeepSpeech2InferModel(DeepSpeech2Model):
             probs: probs after softmax
         """
         eouts, eouts_len = self.encoder(audio, audio_len)
-        probs = self.decoder.probs(eouts)
+        probs = self.decoder.softmax(eouts)
         return probs

deepspeech/modules/ctc.py

@@ -20,10 +20,12 @@ from paddle import nn
 from paddle.nn import functional as F
 from paddle.nn import initializer as I
 
+from deepspeech.modules.loss import CTCLoss
+from deepspeech.utils import ctc_utils
+
 from deepspeech.decoders.swig_wrapper import Scorer
 from deepspeech.decoders.swig_wrapper import ctc_greedy_decoder
 from deepspeech.decoders.swig_wrapper import ctc_beam_search_decoder_batch
-from deepspeech.modules.loss import CTCLoss
 
 logger = logging.getLogger(__name__)
 
@@ -67,38 +69,31 @@ class CTCDecoder(nn.Layer):
             ys_pad (Tenosr): batch of padded character id sequence tensor (B, Lmax)
             ys_lens (Tensor): batch of lengths of character sequence (B)
         Returns:
-            loss (Tenosr): scalar.
+            loss (Tenosr): ctc loss value, scalar.
         """
         logits = self.ctc_lo(F.dropout(hs_pad, p=self.dropout_rate))
         loss = self.criterion(logits, ys_pad, hlens, ys_lens)
         return loss
 
-    def probs(self, eouts: paddle.Tensor, temperature: float=1.0):
+    def softmax(self, eouts: paddle.Tensor, temperature: float=1.0):
         """Get CTC probabilities.
         Args:
             eouts (FloatTensor): `[B, T, enc_units]`
         Returns:
             probs (FloatTensor): `[B, T, odim]`
         """
-        return F.softmax(self.ctc_lo(eouts) / temperature, axis=-1)
-
-    def scores(self, eouts: paddle.Tensor, temperature: float=1.0):
-        """Get log-scale CTC probabilities.
-        Args:
-            eouts (FloatTensor): `[B, T, enc_units]`
-        Returns:
-            log_probs (FloatTensor): `[B, T, odim]`
-        """
-        return F.log_softmax(self.ctc_lo(eouts) / temperature, axis=-1)
+        self.probs = F.softmax(self.ctc_lo(eouts) / temperature, axis=2)
+        return self.probs
 
-    def log_softmax(self, hs_pad: paddle.Tensor) -> paddle.Tensor:
+    def log_softmax(self, hs_pad: paddle.Tensor,
+                    temperature: float=1.0) -> paddle.Tensor:
         """log_softmax of frame activations
         Args:
             Tensor hs_pad: 3d tensor (B, Tmax, eprojs)
         Returns:
             paddle.Tensor: log softmax applied 3d tensor (B, Tmax, odim)
         """
-        return self.scores(hs_pad)
+        return F.log_softmax(self.ctc_lo(hs_pad) / temperature, axis=2)
 
     def argmax(self, hs_pad: paddle.Tensor) -> paddle.Tensor:
         """argmax of frame activations
@@ -109,6 +104,20 @@ class CTCDecoder(nn.Layer):
         """
         return paddle.argmax(self.ctc_lo(hs_pad), dim=2)
 
+    def forced_align(self,
+                     ctc_probs: paddle.Tensor,
+                     y: paddle.Tensor,
+                     blank_id=0) -> list:
+        """ctc forced alignment.
+        Args:
+            ctc_probs (paddle.Tensor): hidden state sequence, 2d tensor (T, D)
+            y (paddle.Tensor): label id sequence tensor, 1d tensor (L)
+            blank_id (int): blank symbol index
+        Returns:
+            paddle.Tensor: best alignment result, (T).
+        """
+        return ctc_utils.forced_align(ctc_probs, y, blank_id)
+
     def _decode_batch_greedy(self, probs_split, vocab_list):
         """Decode by best path for a batch of probs matrix input.
         :param probs_split: List of 2-D probability matrix, and each consists

deepspeech/utils/metric.py → deepspeech/training/scheduler.py

@@ -12,32 +12,45 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import math
 import logging
-from typing import Tuple, List
 
 import paddle
+from paddle.optimizer.lr import LRScheduler
 
 logger = logging.getLogger(__name__)
 
-__all__ = ["th_accuracy"]
+__all__ = ["WarmupLR"]
 
 
-def th_accuracy(pad_outputs: paddle.Tensor,
-                pad_targets: paddle.Tensor,
-                ignore_label: int) -> float:
-    """Calculate accuracy.
-    Args:
-        pad_outputs (Tensor): Prediction tensors (B * Lmax, D).
-        pad_targets (LongTensor): Target label tensors (B, Lmax, D).
-        ignore_label (int): Ignore label id.
-    Returns:
-        float: Accuracy value (0.0 - 1.0).
+class WarmupLR(LRScheduler):
+    """The WarmupLR scheduler
+    This scheduler is almost same as NoamLR Scheduler except for following
+    difference:
+    NoamLR:
+        lr = optimizer.lr * model_size ** -0.5
+             * min(step ** -0.5, step * warmup_step ** -1.5)
+    WarmupLR:
+        lr = optimizer.lr * warmup_step ** 0.5
+             * min(step ** -0.5, step * warmup_step ** -1.5)
+    Note that the maximum lr equals to optimizer.lr in this scheduler.
     """
-    pad_pred = pad_outputs.view(
-        pad_targets.size(0), pad_targets.size(1), pad_outputs.size(1)).argmax(2)
-    mask = pad_targets != ignore_label
-    numerator = paddle.sum(
-        pad_pred.masked_select(mask) == pad_targets.masked_select(mask))
-    denominator = paddle.sum(mask)
-    return float(numerator) / float(denominator)
+
+    def __init__(self,
+                 warmup_steps: Union[int, float]=25000,
+                 learning_rate=1.0,
+                 last_epoch=-1,
+                 verbose=False):
+        assert check_argument_types()
+        self.warmup_steps = warmup_steps
+        super().__init__(learning_rate, last_epoch, verbose)
+
+    def __repr__(self):
+        return f"{self.__class__.__name__}(warmup_steps={self.warmup_steps})"
+
+    def get_lr(self):
+        step_num = self.last_epoch + 1
+        return self.base_lr * self.warmup_steps**0.5 * min(
+            step_num**-0.5, step_num * self.warmup_steps**-1.5)
+
+    def set_step(self, step: int):
+        self.last_epoch = step

deepspeech/training/trainer.py

@@ -131,8 +131,13 @@ class Trainer():
     def save(self):
         """Save checkpoint (model parameters and optimizer states).
         """
+        infos = {
+            "step": self.iteration,
+            "epoch": self.epoch,
+            "lr": self.optimizer.get_lr(),
+        }
         checkpoint.save_parameters(self.checkpoint_dir, self.iteration,
-                                   self.model, self.optimizer)
+                                   self.model, self.optimizer, infos)
 
     def resume_or_load(self):
         """Resume from latest checkpoint at checkpoints in the output 
@@ -141,12 +146,13 @@ class Trainer():
         If ``args.checkpoint_path`` is not None, load the checkpoint, else
         resume training.
         """
-        iteration = checkpoint.load_parameters(
+        infos = checkpoint.load_parameters(
             self.model,
             self.optimizer,
             checkpoint_dir=self.checkpoint_dir,
             checkpoint_path=self.args.checkpoint_path)
-        self.iteration = iteration
+        self.iteration = infos["step"]
+        self.epoch = infos["epoch"]
 
     def new_epoch(self):
         """Reset the train loader and increment ``epoch``.

deepspeech/utils/checkpoint.py

@@ -16,6 +16,8 @@ import os
 import time
 import logging
 import numpy as np
+import re
+import json
 
 import paddle
 from paddle import distributed as dist
@@ -37,15 +39,13 @@ def _load_latest_checkpoint(checkpoint_dir: str) -> int:
         int: the latest iteration number.
     """
     checkpoint_record = os.path.join(checkpoint_dir, "checkpoint")
-    if (not os.path.isfile(checkpoint_record)):
+    if not os.path.isfile(checkpoint_record):
         return 0
 
     # Fetch the latest checkpoint index.
     with open(checkpoint_record, "rt") as handle:
         latest_checkpoint = handle.readlines()[-1].strip()
-        step = latest_checkpoint.split(":")[-1]
-        iteration = int(step.split("-")[-1])
-
+        iteration = int(latest_checkpoint.split(":")[-1])
     return iteration
 
 
@@ -60,7 +60,7 @@ def _save_checkpoint(checkpoint_dir: str, iteration: int):
     checkpoint_record = os.path.join(checkpoint_dir, "checkpoint")
     # Update the latest checkpoint index.
     with open(checkpoint_record, "a+") as handle:
-        handle.write("model_checkpoint_path:step-{}\n".format(iteration))
+        handle.write("model_checkpoint_path:{}\n".format(iteration))
 
 
 def load_parameters(model,
@@ -74,20 +74,16 @@ def load_parameters(model,
             Defaults to None.
         checkpoint_dir (str, optional): the directory where checkpoint is saved.
         checkpoint_path (str, optional): if specified, load the checkpoint
-            stored in the checkpoint_path and the argument 'checkpoint_dir' will 
+            stored in the checkpoint_path(prefix) and the argument 'checkpoint_dir' will 
             be ignored. Defaults to None. 
     Returns:
-        iteration (int): number of iterations that the loaded checkpoint has 
-            been trained.
+        configs (dict): epoch or step, lr and other meta info should be saved.
     """
     if checkpoint_path is not None:
-        iteration = int(os.path.basename(checkpoint_path).split("-")[-1])
+        iteration = int(os.path.basename(checkpoint_path).split(":")[-1])
     elif checkpoint_dir is not None:
         iteration = _load_latest_checkpoint(checkpoint_dir)
-        if iteration == 0:
-            return iteration
-        checkpoint_path = os.path.join(checkpoint_dir,
-                                       "step-{}".format(iteration))
+        checkpoint_path = os.path.join(checkpoint_dir, "-{}".format(iteration))
     else:
         raise ValueError(
             "At least one of 'checkpoint_dir' and 'checkpoint_path' should be specified!"
@@ -98,43 +94,58 @@ def load_parameters(model,
     params_path = checkpoint_path + ".pdparams"
     model_dict = paddle.load(params_path)
     model.set_state_dict(model_dict)
-    logger.info(
-        "[checkpoint] Rank {}: loaded model from {}".format(rank, params_path))
+    logger.info("Rank {}: loaded model from {}".format(rank, params_path))
 
     optimizer_path = checkpoint_path + ".pdopt"
     if optimizer and os.path.isfile(optimizer_path):
         optimizer_dict = paddle.load(optimizer_path)
         optimizer.set_state_dict(optimizer_dict)
-        logger.info("[checkpoint] Rank {}: loaded optimizer state from {}".
-                    format(rank, optimizer_path))
+        logger.info("Rank {}: loaded optimizer state from {}".format(
+            rank, optimizer_path))
 
-    return iteration
+    info_path = re.sub('.pdparams$', '.json', params_path)
+    configs = {}
+    if os.path.exists(info_path):
+        with open(info_path, 'r') as fin:
+            configs = json.load(fin)
+    return configs
 
 
 @mp_tools.rank_zero_only
-def save_parameters(checkpoint_dir, iteration, model, optimizer=None):
+def save_parameters(checkpoint_dir: str,
+                    iteration: int,
+                    model: paddle.nn.Layer,
+                    optimizer: Optimizer=None,
+                    infos: dict=None):
     """Checkpoint the latest trained model parameters.
     Args:
         checkpoint_dir (str): the directory where checkpoint is saved.
-        iteration (int): the latest iteration number.
+        iteration (int): the latest iteration(step or epoch) number.
         model (Layer): model to be checkpointed.
         optimizer (Optimizer, optional): optimizer to be checkpointed.
             Defaults to None.
+        infos (dict or None): any info you want to save.
     Returns:
         None
     """
-    checkpoint_path = os.path.join(checkpoint_dir, "step-{}".format(iteration))
+    checkpoint_path = os.path.join(checkpoint_dir, "-{}".format(iteration))
 
     model_dict = model.state_dict()
     params_path = checkpoint_path + ".pdparams"
     paddle.save(model_dict, params_path)
-    logger.info("[checkpoint] Saved model to {}".format(params_path))
+    logger.info("Saved model to {}".format(params_path))
 
     if optimizer:
         opt_dict = optimizer.state_dict()
         optimizer_path = checkpoint_path + ".pdopt"
         paddle.save(opt_dict, optimizer_path)
-        logger.info(
-            "[checkpoint] Saved optimzier state to {}".format(optimizer_path))
+        logger.info("Saved optimzier state to {}".format(optimizer_path))
+
+    info_path = re.sub('.pdparams$', '.json', params_path)
+    if infos is None:
+        infos = {}
+    with open(info_path, 'w') as fout:
+        data = json.dumps(infos)
+        fout.write(data)
 
     _save_checkpoint(checkpoint_dir, iteration)

deepspeech/utils/cmvn.py

+# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import math
+import logging
+import numpy as np
+
+logger = logging.getLogger(__name__)
+
+__all__ = ['load_cmvn']
+
+
+def _load_json_cmvn(json_cmvn_file):
+    """ Load the json format cmvn stats file and calculate cmvn
+    Args:
+        json_cmvn_file: cmvn stats file in json format
+    Returns:
+        a numpy array of [means, vars]
+    """
+    with open(json_cmvn_file) as f:
+        cmvn_stats = json.load(f)
+
+    means = cmvn_stats['mean_stat']
+    variance = cmvn_stats['var_stat']
+    count = cmvn_stats['frame_num']
+    for i in range(len(means)):
+        means[i] /= count
+        variance[i] = variance[i] / count - means[i] * means[i]
+        if variance[i] < 1.0e-20:
+            variance[i] = 1.0e-20
+        variance[i] = 1.0 / math.sqrt(variance[i])
+    cmvn = np.array([means, variance])
+    return cmvn
+
+
+def _load_kaldi_cmvn(kaldi_cmvn_file):
+    """ Load the kaldi format cmvn stats file and calculate cmvn
+    Args:
+        kaldi_cmvn_file:  kaldi text style global cmvn file, which
+           is generated by:
+           compute-cmvn-stats --binary=false scp:feats.scp global_cmvn
+    Returns:
+        a numpy array of [means, vars]
+    """
+    means = []
+    variance = []
+    with open(kaldi_cmvn_file, 'r') as fid:
+        # kaldi binary file start with '\0B'
+        if fid.read(2) == '\0B':
+            logger.error('kaldi cmvn binary file is not supported, please '
+                         'recompute it by: compute-cmvn-stats --binary=false '
+                         ' scp:feats.scp global_cmvn')
+            sys.exit(1)
+        fid.seek(0)
+        arr = fid.read().split()
+        assert (arr[0] == '[')
+        assert (arr[-2] == '0')
+        assert (arr[-1] == ']')
+        feat_dim = int((len(arr) - 2 - 2) / 2)
+        for i in range(1, feat_dim + 1):
+            means.append(float(arr[i]))
+        count = float(arr[feat_dim + 1])
+        for i in range(feat_dim + 2, 2 * feat_dim + 2):
+            variance.append(float(arr[i]))
+
+    for i in range(len(means)):
+        means[i] /= count
+        variance[i] = variance[i] / count - means[i] * means[i]
+        if variance[i] < 1.0e-20:
+            variance[i] = 1.0e-20
+        variance[i] = 1.0 / math.sqrt(variance[i])
+    cmvn = np.array([means, variance])
+    return cmvn
+
+
+def load_cmvn(cmvn_file, is_json):
+    if is_json:
+        cmvn = _load_json_cmvn(cmvn_file)
+    else:
+        cmvn = _load_kaldi_cmvn(cmvn_file)
+    return cmvn[0], cmvn[1]

deepspeech/utils/ctc_utils.py

+# Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import numpy as np
+from typing import List
+
+import paddle
+
+logger = logging.getLogger(__name__)
+
+__all__ = ["forced_align", "remove_duplicates_and_blank", "insert_blank"]
+
+
+def remove_duplicates_and_blank(hyp: List[int], blank_id=0) -> List[int]:
+    """ctc alignment to ctc label ids.
+
+    "abaa-acee-" -> "abaace"
+
+    Args:
+        hyp (List[int]): hypotheses ids, (L)
+        blank_id (int, optional): blank id. Defaults to 0.
+
+    Returns:
+        List[int]: remove dupicate ids, then remove blank id.
+    """
+    new_hyp: List[int] = []
+    cur = 0
+    while cur < len(hyp):
+        if hyp[cur] != blank_id:
+            new_hyp.append(hyp[cur])
+        prev = cur
+        while cur < len(hyp) and hyp[cur] == hyp[prev]:
+            cur += 1
+    return new_hyp
+
+
+def insert_blank(label: np.ndarray, blank_id: int=0):
+    """Insert blank token between every two label token.
+
+    "abcdefg" -> "-a-b-c-d-e-f-g-"
+
+    Args:
+        label ([np.ndarray]): label ids, (L).
+        blank_id (int, optional): blank id. Defaults to 0.
+
+    Returns:
+        [np.ndarray]: (2L+1).
+    """
+    label = np.expand_dims(label, 1)  #[L, 1]
+    blanks = np.zeros((label.shape[0], 1), dtype=np.int64) + blank_id
+    label = np.concatenate([blanks, label], axis=1)  #[L, 2]
+    label = label.reshape(-1)  #[2L]
+    label = np.append(label, label[0])  #[2L + 1]
+    return label
+
+
+def forced_align(ctc_probs: paddle.Tensor, y: paddle.Tensor,
+                 blank_id=0) -> list:
+    """ctc forced alignment.
+
+    https://distill.pub/2017/ctc/
+
+    Args:
+        ctc_probs (paddle.Tensor): hidden state sequence, 2d tensor (T, D)
+        y (paddle.Tensor): label id sequence tensor, 1d tensor (L)
+        blank_id (int): blank symbol index
+    Returns:
+        paddle.Tensor: best alignment result, (T).
+    """
+    y_insert_blank = insert_blank(y, blank_id)
+
+    log_alpha = paddle.zeros(
+        (ctc_probs.size(0), len(y_insert_blank)))  #(T, 2L+1)
+    log_alpha = log_alpha - float('inf')  # log of zero
+    state_path = (paddle.zeros(
+        (ctc_probs.size(0), len(y_insert_blank)), dtype=paddle.int16) - 1
+                  )  # state path
+
+    # init start state
+    log_alpha[0, 0] = ctc_probs[0][y_insert_blank[0]]  # Sb
+    log_alpha[0, 1] = ctc_probs[0][y_insert_blank[1]]  # Snb
+
+    for t in range(1, ctc_probs.size(0)):
+        for s in range(len(y_insert_blank)):
+            if y_insert_blank[s] == blank_id or s < 2 or y_insert_blank[
+                    s] == y_insert_blank[s - 2]:
+                candidates = paddle.to_tensor(
+                    [log_alpha[t - 1, s], log_alpha[t - 1, s - 1]])
+                prev_state = [s, s - 1]
+            else:
+                candidates = paddle.to_tensor([
+                    log_alpha[t - 1, s],
+                    log_alpha[t - 1, s - 1],
+                    log_alpha[t - 1, s - 2],
+                ])
+                prev_state = [s, s - 1, s - 2]
+            log_alpha[t, s] = paddle.max(candidates) + ctc_probs[t][
+                y_insert_blank[s]]
+            state_path[t, s] = prev_state[paddle.argmax(candidates)]
+
+    state_seq = -1 * paddle.ones((ctc_probs.size(0), 1), dtype=paddle.int16)
+
+    candidates = paddle.to_tensor([
+        log_alpha[-1, len(y_insert_blank) - 1],  # Sb
+        log_alpha[-1, len(y_insert_blank) - 2]  # Snb
+    ])
+    prev_state = [len(y_insert_blank) - 1, len(y_insert_blank) - 2]
+    state_seq[-1] = prev_state[paddle.argmax(candidates)]
+    for t in range(ctc_probs.size(0) - 2, -1, -1):
+        state_seq[t] = state_path[t + 1, state_seq[t + 1, 0]]
+
+    output_alignment = []
+    for t in range(0, ctc_probs.size(0)):
+        output_alignment.append(y_insert_blank[state_seq[t, 0]])
+
+    return output_alignment

deepspeech/utils/common.py → deepspeech/utils/tensor_utils.py

@@ -20,7 +20,7 @@ import paddle
 
 logger = logging.getLogger(__name__)
 
-__all__ = ["pad_list", "add_sos_eos", "remove_duplicates_and_blank", "log_add"]
+__all__ = ["pad_list", "add_sos_eos", "th_accuracy"]
 
 IGNORE_ID = -1
 
@@ -90,24 +90,21 @@ def add_sos_eos(ys_pad: paddle.Tensor, sos: int, eos: int,
     return pad_list(ys_in, eos), pad_list(ys_out, ignore_id)
 
 
-def remove_duplicates_and_blank(hyp: List[int]) -> List[int]:
-    new_hyp: List[int] = []
-    cur = 0
-    while cur < len(hyp):
-        if hyp[cur] != 0:
-            new_hyp.append(hyp[cur])
-        prev = cur
-        while cur < len(hyp) and hyp[cur] == hyp[prev]:
-            cur += 1
-    return new_hyp
-
-
-def log_add(args: List[int]) -> float:
-    """
-    Stable log add
+def th_accuracy(pad_outputs: paddle.Tensor,
+                pad_targets: paddle.Tensor,
+                ignore_label: int) -> float:
+    """Calculate accuracy.
+    Args:
+        pad_outputs (Tensor): Prediction tensors (B * Lmax, D).
+        pad_targets (LongTensor): Target label tensors (B, Lmax, D).
+        ignore_label (int): Ignore label id.
+    Returns:
+        float: Accuracy value (0.0 - 1.0).
     """
-    if all(a == -float('inf') for a in args):
-        return -float('inf')
-    a_max = max(args)
-    lsp = math.log(sum(math.exp(a - a_max) for a in args))
-    return a_max + lsp
+    pad_pred = pad_outputs.view(
+        pad_targets.size(0), pad_targets.size(1), pad_outputs.size(1)).argmax(2)
+    mask = pad_targets != ignore_label
+    numerator = paddle.sum(
+        pad_pred.masked_select(mask) == pad_targets.masked_select(mask))
\ No newline at end of file
+    denominator = paddle.sum(mask)
+    return float(numerator) / float(denominator)

deepspeech/utils/utility.py

@@ -13,10 +13,13 @@
 # limitations under the License.
 """Contains common utility functions."""
 
+import math
 import numpy as np
 import distutils.util
 
-__all__ = ['print_arguments', 'add_arguments']
+__all__ = [
+    'print_arguments', 'add_arguments', "log_add", "remove_duplicates_and_blank"
+]
 
 
 def print_arguments(args):
@@ -57,4 +60,38 @@ def add_arguments(argname, type, default, help, argparser, **kwargs):
         default=default,
         type=type,
         help=help + ' Default: %(default)s.',
-        **kwargs)
+        **kwargs)
\ No newline at end of file
+
+
+def log_add(args: List[int]) -> float:
+    """
+    Stable log add
+    """
+    if all(a == -float('inf') for a in args):
+        return -float('inf')
+    a_max = max(args)
+    lsp = math.log(sum(math.exp(a - a_max) for a in args))
+    return a_max + lsp
+
+
+def remove_duplicates_and_blank(hyp: List[int], blank_id=0) -> List[int]:
+    """ctc alignment to ctc label ids.
+
+    "abaa-acee-" -> "abaace"
+
+    Args:
+        hyp (List[int]): hypotheses ids, (L)
+        blank_id (int, optional): blank id. Defaults to 0.
+
+    Returns:
+        List[int]: remove dupicate ids, then remove blank id.
+    """
+    new_hyp: List[int] = []
+    cur = 0
+    while cur < len(hyp):
+        if hyp[cur] != blank_id:
+            new_hyp.append(hyp[cur])
+        prev = cur
+        while cur < len(hyp) and hyp[cur] == hyp[prev]:
+            cur += 1
+    return new_hyp