[GitHub] [incubator-mxnet] windoman opened a new issue #14548: mx.viz.plot_network KeyError: 'ctc_loss0_output'

[GitBox <gi...@apache.org>]

windoman opened a new issue #14548: mx.viz.plot_network KeyError: 'ctc_loss0_output'
URL: https://github.com/apache/incubator-mxnet/issues/14548
 
 
   ## Description
   
   I builded my network with `mx.sym.ctc_loss` for the final loss on speech recognition task, and with `mx.viz.plot_network` to make sure that the network have right struct. But I got an exception as invoking `mx.viz.plot_network`, even the symbol of network as simple as possible.
   
   ## Environment info (Required)
   
   operating system: ubuntu-16.04 LTS
   python version: python 3.5
   mxnet version: 1.4.0-cpu
   
   ## Error Message:
   
   ```
   Traceback (most recent call last):
     File "ctc_plot.py", line 21, in <module>
       mx.viz.plot_network(sym, shape=shape).view()
     File "/home/windog/.local/lib/python3.5/site-packages/mxnet/visualization.py", line 382, in plot_network
       shape = shape_dict[key][1:]
   KeyError: 'ctc_loss0_output'
   ```
   
   ## Minimum reproducible example
   (If you are using your own code, please provide a short script that reproduces the error. Otherwise, please provide link to the existing example.)
   
   **ctc_plot.py**:
   
   ``` python
   import mxnet as mx
   
   def ctc_sym():
       data = mx.sym.Variable('data')
       label = mx.sym.Variable('label')
       data_len = mx.sym.Variable('data_len')
       label_len = mx.sym.Variable('label_len')
   
       ctc_loss = mx.sym.ctc_loss(data, label, data_len, label_len, True, True)
       ctc_loss = mx.sym.MakeLoss(ctc_loss)
   
       return ctc_loss
   
   
   if __name__ == '__main__':
       shape = {'data': (400, 32, 100),   # [max_seq_len, batch_size, num_cls]
               'label': (32, 50),         # [batch_size, max_label_len]
               'data_len': (32,),         # [batch_size,]
               'label_len': (32,)}        # [batch_size,]
       sym = ctc_sym()
       mx.viz.plot_network(sym, shape=shape).view()
   ```
   
   ## Steps to reproduce
   (Paste the commands you ran that produced the error.)
   
   1. python3 ctc_plot.py
   
   ## What have you tried to solve it?
   
   1. there is a related issue: [#3221](https://github.com/apache/incubator-mxnet/issues/3221)
   2. I have debugged into `incubator-mxnet/python/mxnet/visualization.py` in which throw a exception, and got a wrong `key` for `shape_dict` in following position in `visualization.py`:
   
   ![image](https://user-images.githubusercontent.com/9418558/55126339-b56f2a00-5147-11e9-9bcc-1b9d46482598.png)
   
   And then, I found out that the input name of symbol of `MakeLoss(ctc_loss)`, `ctc_loss0_output0`, has a bit difference from `key = input_name + "_output"` which is `ctc_loss0_output`.  And shape variable `shape_dict` is given by following code in `visualization.py`:
   
   ![image](https://user-images.githubusercontent.com/9418558/55127050-ccaf1700-5149-11e9-962b-d3f90a63cebc.png)
   
   The definition of `list_outputs` which is located at line 734 of `mxnet/model/symbol.py`:
   
   ![image](https://user-images.githubusercontent.com/9418558/55127012-b012df00-5149-11e9-878b-0ae90fe83b9a.png)
   
   I could not deep into as its' low-level implement, so is there anyone to help me out. What raise that exception? Wrong invoking of `ctc_loss` or `plot_network`, or some inner mistakes in mxnet?

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