title: can't get ROUGE score with pyrouge
body: <p>I was carrying out an experiment on text summarization. After getting the decoded sentences and reference sentences, I used pyrouge to obtain the ROUGE score, the python code is as follows:</p>
  
  <pre><code>from pyrouge import Rouge155
  r=Rouge155()
  r.model_filename_pattern = '#ID#——reference.txt'
  r.system_filename_pattern = '(\d+)_decoded.txt'
  r.model_dir = '/home/test/reference'
  r.system_dir = '/home/test/decoded'
  
  rouge_results = r.convert_and_evaluate()
  print rouge_results
  output_dict = r.output_to_dict(output)
  </code></pre>
  
  <p>but it didn't seem to work, it reported a <code>subprocess.CalledProcessError</code> and</p>
  
  <pre><code>Illegal division by zero at /.../.../ROUGE/RELEASE-1.5.5/ROUGE-1.5.5.pl
  </code></pre>
  
  <p>Here's the specific error information:</p>
  
  <pre><code>Traceback (most recent call last):
     File "rouge.py", line 28, in &lt;module&gt;
         rouge_results = r.convert_and_evaluate()
     File "/home/username/env/local/lib/python2.7/site-packages/pyrouge-0.1.3.py2.7.egg/pyrouge/Rouge155.py", line 364, in convert_and_evaluate
         rouge_output = self.evaluate(system_id, rouge_args)
     File "/home/username/env/local/lib/python2.7/site-packages/pyrouge-0.1.3.py2.7.egg/pyrouge/Rouge155.py", line 339, in evaluate
         rouge_output = check_output(command).decode("UTF-8")
     File "/usr/lib/python2.7/subprocess.py", line 574, in check_output
         raise CalledProcessError(retcode, cmd, output=output)
  subprocess.CalledProcessError: Command '[u'/home/username/env/ROUGE/RELEASE-1.5.5/ROUGE-1.5.5.pl', '-e', '/home/username/env/ROUGE/RELEASE-1.5.5/data', '-c', '95','-2', '-1', '-U', '-r', '1000', '-n','4','-w','1.2','-a',u'-m', u' /tmp/tmpG9VKo9/rouge_conf.xml']' returned non-zero exit status 255
  </code></pre>
  
  <p>Has anyone come across this kind of issue? Appreciate any suggestion! Many thanks!</p>