title: Identifying the frequency of items in the list
body: <p>I have a dataframe like below.</p>
  
  <pre><code>11,15,12,25
  11,12
  15,25
  134,45,56
  46
  45,56
  15,12
  66,45,56,24,14,11,25,12,134
  </code></pre>
  
  <p>I want to identify the frequency of pairs/triplets or higher that occurs in the data. Say for example, in above data the occurrence of pairs looks like below</p>
  
  <pre><code>item     No of occurrence
  11,12      3
  11,25      2
  15,12      2
  15,25      2
  .
  .
  45,56      3
  134,45,56  2    ....and so on
  </code></pre>
  
  <p>I am trying to write a R code for the above and I am finding difficulty to approach this.</p>