title: R shiny reactive table, render plot can not work
body: <p>everyone. I am very new to shiny. I would like to plot a pie chart based on a filter data frame.
  Here is my data frame:</p>
  
  <pre><code>Duration                Received     Name       Status
  1 month                 01/14/2014   Tim        Completed
  1 month                 02/12/2014   Chris      Completed
  2 months                01/08/2015   Anna       Completed
  1 month                 06/25/2014   Jenifer    Completed
  2 months                05/14/2015   Ruby       Completed
  more than 3 months      11/05/2014   David      Pending
  2 months                05/12/2015   Anna       Completed
  1 months                03/26/2015   David      Completed
  ...  ...
  </code></pre>
  
  <p>There may be more than 500 lines in the data frame</p>
  
  <p>First, I tried to subset the data frame by Received Date. And plot the Duration Freq in pie chart. For example, I would like to choose all records after 12/31/2014. So I can select my Received Date. Then, table() Duration column in the subset data frame. Last, plot the pie chart.</p>
  
  <p>My problem is when I change the date Rang of the Received date, my pie plot keep the consistent, never update. Can anyone help me to debug my script and tell me why? Thank you</p>
  
  <p>Here is my code: 
  ui.R</p>
  
  <pre><code>library(shiny)
  library(ggplot2)
  ggpie &lt;- function (dat, by, totals) {
      ggplot(dat, aes_string(x=factor(1), y=totals, fill=by)) +
      geom_bar(stat='identity', color='black') +
      guides(fill=guide_legend(override.aes=list(colour=NA))) + 
      coord_polar(theta='y') +
      theme(axis.ticks=element_blank(),
            axis.text.y=element_blank(),
            axis.text.x = element_blank(),
            axis.title=element_blank()) +
      scale_y_continuous(breaks=cumsum(dat[[totals]]) - dat[[totals]] / 2,       labels=dat[[by]])    
  }
  shinyUI(fluidPage(
    headerPanel("My App"),  
    sidebarPanel(     
      dateRangeInput("dates", label = h3("Received Date Range"),
                 start = "2013-01-01",
                 end = as.character(Sys.Date())
      )
    ),   
    mainPanel(
      plotOutput("Duration"),
      tableOutput("test")
    )
  ))
  </code></pre>
  
  <p>server.R</p>
  
  <pre><code>library(shiny)
  library(ggplot2)
  ggpie &lt;- function (dat, by, totals) {
    ggplot(dat, aes_string(x=factor(1), y=totals, fill=by)) +
      geom_bar(stat='identity', color='black') +
      guides(fill=guide_legend(override.aes=list(colour=NA))) + 
      coord_polar(theta='y') +
      theme(axis.ticks=element_blank(),
            axis.text.y=element_blank(),
            axis.text.x = element_blank(),
            #axis.text.x=element_text(colour='black',angle=45, size=10, vjust=0.5),
            axis.title=element_blank()) +
      scale_y_continuous(breaks=cumsum(dat[[totals]]) - dat[[totals]] / 2, labels=dat[[by]])    
  }    
  shinyServer(function(input, output) {
    #table
    newData= reactive({
      data1 = subset(data, input$dates[1]&lt;=data$Received &amp;&amp; data$Received&lt;=input$dates[2])
      data2 = as.data.frame(table(data1$Duration))
    })
    output$test&lt;- renderTable({
      newData()
    })
    output$Duration&lt;-renderPlot({    
      ggpie(newData(), by='Var1', totals="Freq") +
        ggtitle("Duration")+
        scale_fill_discrete(name="Duration")    
    })
  })
  </code></pre>