title: After installing can't run the functions of matplotlib library
body: <p>Recently after I installed matplotlib, I can't run its library functions. It is showing error message as if matplotlib is not installed.</p>
  
  <p>I already have Python 3.7 installed in my windows 10 computer and it is working fine both for the interpreter and for the IDLE. After I install matplotlib, the status was ok: </p>
  
  <pre><code>"Successfully installed cycler-0.10.0 kiwisolver-1.1.0 matplotlib-3.1.1 numpy-1.16.4 pyparsing-2.4.0 python-dateutil-2.8.0"
  </code></pre>
  
  <p>But when I tried to run any function from the matplotlib library it was showing an error:</p>
  
  <p><strong>Code:</strong></p>
  
  <pre><code>from nltk.corpus import udhr
  
  languages = ['Chickasaw', 'English', 'German_Deutsch', 'Greenlandic_Inuktikut', 'Hungarian_Magyar', 'Ibibio_Efik']
  cfd = nltk.ConditionalFreqDist((lang, len(word)) for lang in languages for word in udhr.words(lang + '-Latin1'))
  cfd.plot()
  </code></pre>
  
  <p><strong>Error:</strong></p>
  
  <pre class="lang-none prettyprint-override"><code>Traceback (most recent call last):
  
    File "C:\Users\hp\AppData\Local\Programs\Python\Python37-32\lib\site-packages\nltk\probability.py", line 1907, in plot
      from matplotlib import plt
  ImportError: cannot import name 'plt' from 'matplotlib' (C:\Users\hp\AppData\Local\Programs\Python\Python37-32\lib\site-packages\matplotlib\__init__.py)
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
  
    File "&lt;pyshell#6&gt;", line 1, in &lt;module&gt;
      cfd.plot()
    File "C:\Users\hp\AppData\Local\Programs\Python\Python37-32\lib\site-packages\nltk\probability.py", line 1910, in plot
      'The plot function requires matplotlib to be installed.'
  ValueError: The plot function requires matplotlib to be installed.See http://matplotlib.org/`
  </code></pre>