1 files changed, 26 insertions, 0 deletions
diff --git a/swr2_asr/utils/decoder.py b/swr2_asr/utils/decoder.py
new file mode 100644
index 0000000..fcddb79
--- /dev/null
+++ b/swr2_asr/utils/decoder.py
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+"""Decoder for CTC-based ASR.""" ""
+import torch
+
+from swr2_asr.utils.tokenizer import CharTokenizer
+
+
+# TODO: refactor to use torch CTC decoder class
+def greedy_decoder(output, labels, label_lengths, tokenizer: CharTokenizer, collapse_repeated=True):
+    """Greedily decode a sequence."""
+    blank_label = tokenizer.get_blank_token()
+    arg_maxes = torch.argmax(output, dim=2)  # pylint: disable=no-member
+    decodes = []
+    targets = []
+    for i, args in enumerate(arg_maxes):
+        decode = []
+        targets.append(tokenizer.decode(labels[i][: label_lengths[i]].tolist()))
+        for j, index in enumerate(args):
+            if index != blank_label:
+                if collapse_repeated and j != 0 and index == args[j - 1]:
+                    continue
+                decode.append(index.item())
+        decodes.append(tokenizer.decode(decode))
+    return decodes, targets
+
+
+# TODO: add beam search decoder