title: pyparsing example
body: <p>It is my first attempt to use pyparsing and I'd like to ask
  how to filter this sample line:</p>
  
  <pre><code>survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812'''
  </code></pre>
  
  <p>to get output like: 1,52.125133215643,21.031048525561,116.898812</p>
  
  <p>In general I have problem with understanding pyparsing logic so any help with this
  example will be appreciated. Thanks</p>