InvalidArgumentError: Labels length is zero in batch in ctc_loss function

[Ammiit]

I am getting this error while training the model for line by line handwritten text recognition after training with some batches.

2018-12-10 15:15:10.154857: W tensorflow/core/framework/op_kernel.cc:1318] OP_REQUIRES failed at ctc_loss_op.cc:166 : Invalid argument: Labels length is zero in batch 37
Traceback (most recent call last):
File "main.py", line 143, in
main()
File "main.py", line 130, in main
train(model, loader)
File "main.py", line 34, in train
loss = model.trainBatch(batch)
File "/home/dell/FAQ/SimpleHTR/src/Model.py", line 215, in trainBatch
(_, lossVal) = self.sess.run([self.optimizer, self.loss], { self.inputImgs : batch.imgs, self.gtTexts : sparse , self.seqLen : [Model.maxTextLen] * Model.batchSize, self.learningRate : rate} )
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 900, in run
run_metadata_ptr)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1135, in _run
feed_dict_tensor, options, run_metadata)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1316, in _do_run
run_metadata)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 1335, in _do_call
raise type(e)(node_def, op, message)
tensorflow.python.framework.errors_impl.InvalidArgumentError: Labels length is zero in batch 37
[[Node: CTCLoss = CTCLoss[ctc_merge_repeated=true, ignore_longer_outputs_than_inputs=true, preprocess_collapse_repeated=false, _device="/job:localhost/replica:0/task:0/device:CPU:0"](transpose, _arg_Placeholder_1_0_1, _arg_Placeholder_2_0_2, _arg_Placeholder_4_0_4)]]

Caused by op u'CTCLoss', defined at:
File "main.py", line 143, in
main()
File "main.py", line 129, in main
model = Model(loader.charList, decoderType)
File "/home/dell/FAQ/SimpleHTR/src/Model.py", line 34, in init
(self.loss, self.decoder) = self.setupCTC(rnnOut3d)
File "/home/dell/FAQ/SimpleHTR/src/Model.py", line 104, in setupCTC
loss = tf.nn.ctc_loss(labels=self.gtTexts, inputs=ctcIn3dTBC, ignore_longer_outputs_than_inputs=True,sequence_length=self.seqLen, ctc_merge_repeated=True)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/ops/ctc_ops.py", line 158, in ctc_loss
ignore_longer_outputs_than_inputs=ignore_longer_outputs_than_inputs)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/ops/gen_ctc_ops.py", line 285, in ctc_loss
name=name)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/framework/op_def_library.py", line 787, in _apply_op_helper
op_def=op_def)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 3392, in create_op
op_def=op_def)
File "/home/dell/FAQ/virenv_scrap/local/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 1718, in init
self._traceback = self._graph._extract_stack() # pylint: disable=protected-access

[githubharald]

Do you use the IAM dataset or some other dataset? It seems like one of the ground-truth-texts has length 0, which can't be handled by the ctc_loss TensorFlow implementation.

To find out if this is the case, add the following code after this code line:

if gtText == '':
	print('Found sample with empty text:', line)
	continue

This should print and ignore the samples with empty texts.

If this is not the case, then I need more information - please fill out the issue template.

[Ammiit]

Thanks it solved the error I was using RIMES dataset.