title: Replace a transaction type data table with item number from a different table using R
body: <p>First we have a transaction data, we can use the built in dataset. </p>
  
  <pre><code>require(arules)
  
  ## Can use built-in example dataset
  require(datasets)
  data(Groceries)
  
  groceries &lt;- as ( "transactions") # convert to 'transactions' class
  
  summary(groceries)
  </code></pre>
  
  <p>And the output is:</p>
  
  <pre><code>most frequent items:
    whole milk other vegetables       rolls/buns             soda           yogurt          (Other) 
          2513             1903             1809             1715             1372            34055 
  </code></pre>
  
  <p>But then we have another data table that we want to data use for labeling:  </p>
  
  <pre><code>itemnum &lt;- c(1,2,3,4,5)
  ProductName_ &lt;- factor(c("whole milk", "other vegetables", "rolls/buns", "soda", "yogurt"))
  ProductNames &lt;- data.frame(itemnum, ProductName_)
  </code></pre>
  
  <p>How can I replace the product description on the first table with the itemnum from the second?</p>
  
  <p>So when I run:</p>
  
  <pre><code>summary(groceries)
  </code></pre>
  
  <p>The output is:</p>
  
  <pre><code>most frequent items:
       1      2       3      4       5       (Other) 
    2513   1903    1809   1715    1372         34055 
  </code></pre>