title: processing natural language that descripe time frequency with R
body: <p>I'm dealing with data that descripe onset frequency of a symptom. The text in each cell was not in the same format. For example:</p>
  <pre><code>&quot;Pattern 1: 1-3/months, Pattern 2: 6 times per month&quot;                                                                                                                   
  &quot;4-5 times/day&quot;                                                                                                                                                          
  &quot;10 times/day to 7-8 times/week&quot;                                                                                                                                         
  &quot;varies (average 0-10 fits/month)&quot;                                                                                                                                       
  &quot;1-2 times/month, but 2-3/week in recent 3 months\n&quot;                                                                                                                     
  &quot;2-3/month&quot;
  </code></pre>
  <p>What I'm trying to do is to generate the minimum and maximum frequency of each description for further statistical analysis. I can try to complete this job by regular expression, although it might not be very efficient. I'm very new to natural lauguage processing, is there a more efficient way to do this other than the regular expression way? Thanks!</p>
  <p>I can read and type the frequency by hand. But from what I've learned, this is always a bad practice to data analysis.</p>
  <p>(Sorry about not being able to ask the question in a more specific way.)</p>