title: importing .py file error
body: <p>I am trying to import .py file and it gives the error.</p>
  
  <pre><code>import thinkplot
  </code></pre>
  
  <p>And the error : </p>
  
  <blockquote>
    <p>Traceback (most recent call last):
      File "", line 1, in 
        import thinkplot
    ImportError: No module named thinkplotTraceback (most recent call last):
      File "", line 1, in 
        import thinkplot
    ImportError: No module named thinkplot</p>
  </blockquote>
  
  <p>But when I open <code>thinkplot.py</code> file and then writing the code <code>import thinkplot</code>, it works well. But without opening the file, it doesn't work.</p>
  
  <p>There are similar questions in the forum but none of them work for me. I am new to Python. How can I fix the problem ? Also, I am using python 2.7 in a ubuntu linux. Thank you...</p>