From 0151f2463fe00b7d3268fcf07e65fc3d4ea0b991 Mon Sep 17 00:00:00 2001
From: Jackwaterveg <87408988+Jackwaterveg@users.noreply.github.com>
Date: Fri, 17 Dec 2021 11:01:20 +0800
Subject: [PATCH] fix bug of pad_sequence in u2,test=asr (#1153)

---
 paddlespeech/s2t/models/u2/u2.py | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/paddlespeech/s2t/models/u2/u2.py b/paddlespeech/s2t/models/u2/u2.py
index fdcab018..2d6fb218 100644
--- a/paddlespeech/s2t/models/u2/u2.py
+++ b/paddlespeech/s2t/models/u2/u2.py
@@ -579,10 +579,15 @@ class U2BaseModel(ASRInterface, nn.Layer):
             num_decoding_left_chunks, simulate_streaming)
         assert len(hyps) == beam_size
 
-        hyps_pad = pad_sequence([
-            paddle.to_tensor(hyp[0], place=device, dtype=paddle.long)
-            for hyp in hyps
-        ], True, self.ignore_id)  # (beam_size, max_hyps_len)
+        hyp_list = []
+        for hyp in hyps:
+            hyp_content = hyp[0]
+            # Prevent the hyp is empty
+            if len(hyp_content) == 0:
+                hyp_content = (self.ctc.blank_id,)
+            hyp_content = paddle.to_tensor(hyp_content, place=device, dtype=paddle.long)
+            hyp_list.append(hyp_content)
+        hyps_pad = pad_sequence(hyp_list, True, self.ignore_id)
         hyps_lens = paddle.to_tensor(
             [len(hyp[0]) for hyp in hyps], place=device,
             dtype=paddle.long)  # (beam_size,)