title: How to look for multiple data sets for use in Shiny Interactive Document in RStudio?
body: <p>I have started learning about Shiny Interactive documents and am not a programmer so please pardon my ignorance.<br>
  This is based on rmarkdown version 2 website 'Advanced' topics page. I have the RStudio version 0.98.1028.<br>
  I am trying to display the <code>head</code> of vectors <code>a</code> or <code>b</code> in the shiny doc. Here's what I did:</p>
  
  <pre><code>```{r two, echo = FALSE}
  
  a &lt;- 1:10
  b &lt;- 13:20
  a
  b
  selectInput("dataset2", "Choose Dataset:", c('a', 'b'))
  
  activeDataset2 &lt;- reactive({
    get(input$dataset2)
  })
  
  renderTable({
    head(activeDataset2(), 5)
  })
  
  ```
  </code></pre>
  
  <p>Upon clicking <code>Run Document</code>, I get the Error <code>no applicable method for 'xtable' applied to an object of class "c('integer', 'numeric')"</code>.<br>
  In the example on the website, an argument <code>pos</code> is used to look for the data sets. I don't know how to use that in this context. Please help.</p>