title: Real time chart on R - Shiny
body: <p>I'm trying to make an interactive chart that plots financial stock data on a shiny app. My attempt is to update continuously the data, hence the chart.  I managed this using a package called Highcharter. Below it's shown a part of code in the server part (getDataIntraday() receive two input and returns updated xts).  </p>
  
  <pre><code>getID &lt;- reactive({
    invalidateLater(60000)
    y &lt;- getDataIntraDay(input$text, input$radio)
    return(y)
  })
  
  output$plot1 &lt;- renderHighchart({
  
  y &lt;- getID()
  
  highchart() %&gt;% 
    hc_credits(enabled = TRUE,
    hc_exporting(enabled = TRUE)%&gt;%
    hc_add_series_ohlc(y) %&gt;% 
    hc_add_theme(hc_theme_538(colors = c("red", "blue", "green"),
                              chart = list(backgroundColor = "white")))
  })
  </code></pre>
  
  <p>This works: every 60 seconds the chart and the data are automatically updated. The problem are the following: </p>
  
  <ol>
  <li><p>When the data and the chart is updated, the zoom settled by the user is not    maintained.</p></li>
  <li><p>The chart need too many seconds in order to update itself because it is computed all the structure, instead of only add the last candle. </p></li>
  </ol>
  
  <p>Are there some ways (some package) that allows to update the chart without compute again the entire function? Or, at least, is there a way to fix all the elements in the chart except by the candles?</p>