Reading objects from shinyoutput object are not allowed

rshiny

I am using the following platform and version of R:

platform x86_64-apple-darwin10.8.0
version.string R version 3.0.3 (2014-03-06)

I am new to shiny and I am trying to put a simple app together using the rWBclimate data set, which is a package in R:

http://cran.r-project.org/web/packages/rWBclimate/rWBclimate.pdf

I get the following error:

Error in $.shinyoutput(output, gvis) :
Reading objects from shinyoutput object not allowed.

when using the scripts below.
ui.R

library(shiny)
suppressPackageStartupMessages(library(googleVis))

shinyUI(pageWithSidebar(
  # Application title
  headerPanel("Global Temperature"),

  #sidebar with controls to select var to plot year 
  sidebarPanel(
    selectInput("fromyr", "Select Years:", choices=c("1920", "1940","1960", "1980"))
  ),
  mainPanel(
    htmlOutput("gvis")#, 
  )  

)
)

and server.R

library(shiny)
#install.packages("rWBclimate")
library(rWBclimate)
library(ggplot2)
library(rCharts)
suppressPackageStartupMessages(library(googleVis))

countries <-c("USA","BRA","CAN","YEM")

# get temperature data for ensembles
st=1900
en=2100
data_df_all <- get_ensemble_temp(countries, type="annualavg", start=st, end=en)

data_df<-subset(data_df_all,data_df_all$percentile==50) #subset to median percentile
data_df<-subset(data_df, select=-percentile)
data_df<-subset(data_df, data_df$scenario!="b1")
data_df<-subset(data_df, select=-scenario)
data_df<-subset(data_df, data_df$fromYear==1920)

shinyServer(function(input, output){

  #df<-reactive({
#    switch(subset(data_df, data_df$fromYear==input$fromyr),
#           "1920"= 1920,
#           "1940" = 1940,
#           "1960" = 1960,
#           "1980" = 1980)
    #dfi<-subset(data_df, data_df$fromYear==input$fromyr)
    #subset(data_df, data_df$fromYear==1920)
    #data_df[data_df$fromYear == input$fromyr, ]
    #subset(data_df, data_df$scenario==input$scenar)
    #subset(alldat, alldat$fromYear==input$fromyr)
#  })

  output$gvis < renderGvis({
#    gvisGeoChart(dat=df(), locationvar="locator", colorvar="data")
    gvisGeoChart(data_df, locationvar="locator", colorvar="data")
  })
})

Any insights would be great. I tried using the reactive statement, as well as putting the file directly into gvisGeoChart, as is the version above.

Best Answer

You are only missing a '-' at the end of your server.R file. If you look closely at your output$gvis you will notice that you are not assigning output$gvis but actually comparing it to your rendered Gvis object with the < operator (which is why you get the error about reading objects from output). Just change the output$gvis < renderGvis({... to output$gvis <- renderGvis({... and everything should work fine.

Related Solutions

Reading objects from shiny output object not allowed

The issue is that the output object is generating all of the web display stuff as well. Instead, you need to pull the data separately for the download. You could do it with a second call to brushedPoints in the download code. Better, however, is to use a reactive() function to do it just once, then call that everywhere that you need it. Here is how I would modify your code to make that work:

data(iris)

ui <- basicPage(
  plotOutput("plot1", brush = "plot_brush"),
  verbatimTextOutput("info"),mainPanel(downloadButton('downloadData', 'Download'))
)


server <- function(input, output) {
  output$plot1 <- renderPlot({
    ggplot(iris,aes(x=Sepal.Width,y=Sepal.Length)) + geom_point(aes(color=factor(Species))) + theme_bw()
  })


  selectedData <- reactive({
    brushedPoints(iris, input$plot_brush)
  })

  output$info <- renderPrint({
    selectedData()
  })

  output$downloadData <- downloadHandler(
    filename = function() { 
      paste('SelectedRows', '.csv', sep='') },
    content = function(file) {
      write.csv(selectedData(), file)
    }
  )

}


shinyApp(ui, server)

(Note, with ggplot2, you do not need to explicitly set xvar and yvar in brushedPoints. So, I removed it here to increase the flexibility of the code.)

I am not aware of any "lasso" style free drawing ability in shiny (though, give it a week -- they are constantly adding fun tools). However, you can mimic the behavior by allowing user to select multiple regions and/or to click on individual points. The server logic gets a lot messier, as you need to store the results in a reactiveValues object to be able to use it repeatedly. I have done something similar to allow me to select points on one plot and highlight/remove them on other plots. That is more complicated than what you need here, but the below should work. You may want to add other buttons/logic (e.g., to "reset" the selections), but I believe that this should work. I did add a display of the selection to the plot to allow you to keep track of what has been selected.

data(iris)

ui <- basicPage(
  plotOutput("plot1", brush = "plot_brush", click = "plot_click")
  , actionButton("toggle", "Toggle Seletion")
  , verbatimTextOutput("info")
  , mainPanel(downloadButton('downloadData', 'Download'))
)


server <- function(input, output) {
  output$plot1 <- renderPlot({

    ggplot(withSelected()
           , aes(x=Sepal.Width
                 , y=Sepal.Length
                 , color=factor(Species)
                 , shape = Selected)) +
      geom_point() +
      scale_shape_manual(
        values = c("FALSE" = 19
                   , "TRUE" = 4)
      , labels = c("No", "Yes")
      , name = "Is Selected?"
      ) +
      theme_bw()
  })

  # Make a reactive value -- you can set these within other functions
  vals <- reactiveValues(
    isClicked = rep(FALSE, nrow(iris))
  )


  # Add a column to the data to ease plotting
  # This is really only necessary if you want to show the selected points on the plot
  withSelected <- reactive({
    data.frame(iris
               , Selected = vals$isClicked)
  })



  # Watch for clicks
  observeEvent(input$plot_click, {

    res <- nearPoints(withSelected()
                      , input$plot_click
                      , allRows = TRUE)

    vals$isClicked <-
      xor(vals$isClicked
          , res$selected_)
  })


  # Watch for toggle button clicks
  observeEvent(input$toggle, {
    res <- brushedPoints(withSelected()
                         , input$plot_brush
                         , allRows = TRUE)

    vals$isClicked <-
      xor(vals$isClicked
          , res$selected_)
  })

  # pull the data selection here
  selectedData <- reactive({
    iris[vals$isClicked, ]
  })

  output$info <- renderPrint({
    selectedData()
  })

  output$downloadData <- downloadHandler(
    filename = function() { 
      paste('SelectedRows', '.csv', sep='') },
    content = function(file) {
      write.csv(selectedData(), file)
    }
  )

}


shinyApp(ui, server)

Best Answer

Related Solutions

Reading objects from shiny output object not allowed

Related Topic