title: shiny datatable in landscape orientation
body: <p>I have code as following in shiny</p>
  
  <pre><code>DT::renderDataTable({ 
    df()
    , rownames=FALSE
    ,extensions = c('Responsive', 'Buttons')
    , options = list(
      # dom = 'C&lt;"clear"&gt;T&lt;"clear"&gt;lfrtip'
      # , tableTools=list(sSwfPath = copySWF('www'))
      dom = 'Bfrtip'
      , buttons = c('pageLength'
                    , 'colvis'
                    , 'pdf')
      , orientation ='landscape'
      , lengthMenu = list(c(6, 12, 18, -1), c('6', '12', '18', 'All'))
      , pageLength = 12
      )
    )
  }
  })
  </code></pre>
  
  <p>I want to download pdf in landscape. How should I do it. </p>
  
  <p>According to following link: <a href="https://datatables.net/reference/button/pdf" rel="nofollow">https://datatables.net/reference/button/pdf</a> that we can pass orientation as landscape. However, I am not able to do it.</p>
  
  <p>I have tried following:</p>
  
  <pre><code>DT::renderDataTable({ 
    df()
    , rownames=FALSE
    ,extensions = c('Responsive', 'Buttons')
    , options = list(
      # dom = 'C&lt;"clear"&gt;T&lt;"clear"&gt;lfrtip'
      # , tableTools=list(sSwfPath = copySWF('www'))
      dom = 'Bfrtip'
      , buttons = c('pageLength'
                    , 'colvis'
                    , list(extend: 'pdf', orientation='landscape')
      , orientation ='landscape'
      , lengthMenu = list(c(6, 12, 18, -1), c('6', '12', '18', 'All'))
      , pageLength = 12
      )
    )
  }
  })
  </code></pre>