How to render ggplot from a function that returns a list of multiple objects in Shiny

Question

I have an r script includes a Identify_IP() that returns a list of dataframe and a ggplot. I want to call the script and render both the dataframe and the plot.

This is Identify_IP() function. I took off unrelative code and kept only the plot, lines and ggplot code to give a clear example of my type of ggplot.

library(ggplot2)
library(matrixStats)
library(fda.usc)

#df <- read.table("name.XLS", header = FALSE)

Identify_IP = function(df1){
  mlearn <- df1[,'V7']
     formul <- plot(blue_curve$x, blue_curve$y * 30, type = 'l', col = 'blue')

  formula_deriv <- lines(blue_curve$x, red_curve$y1 * 30, col = 'red')

  p <- ggplot(df1, aes(blue_curve$x)) + 
    geom_line(aes(y = blue_curve$y, colour = "0 Deriv")) + 
    geom_line(aes(y = red_curve$y1, colour = "1st Deriv")) + 
    geom_vline(xintercept = x_loc) + geom_hline(yintercept = 0)


  return(list(df1,p))

}

Now, this is a modified Shiny code based on amrr and micstr suggestion.

 source('InflectionP2.R', local = TRUE)

library(ggplot2)
library(shiny)
runApp(
  list(
    ui = fluidPage(
      titlePanel("Upload your file"),
      sidebarLayout(
        sidebarPanel(
          fileInput('file1', 'Choose xls file',
                    accept = c(".XLS")),

      actionButton("btn", "Update Table"),
      actionButton("btn1", "Display Plot")

    ),

    mainPanel(

      tableOutput('what'),
      plotOutput('pl'))
  )

)
,

server = function(input, output, session){

  dataOP <- reactive({
    inFile <- input$file1
    if (is.null(input$file1))
      return(NULL)

    dfs <- Identify_IP(read.table(inFile$datapath))

    return(dfs)
  })


  observeEvent(input$btn, output$what <-  renderTable({

    dataOP()[[1]]

  }))

  observeEvent(input$btn1, output$pl <- renderPlot({

    pp <- dataOP()

    pp[[2]]

  }))             
}))

This was really helpful in teaching me how to call r script in reactive(). And it makes sense to me. Yet, it render the table but the Display Plot button is not rendering the plot. Does my ggplot in Identify_IP function has anything to do with not being able to display the plot? I also tried print(ggplot(pp[[2]])) and still the same.

How are you returning ggplot in that function? just an assignment like p <- ggplot() ? — amrrs
– amrrs, Commented Nov 9, 2017 at 7:01
And I couldn't see any plot in dataOP() It's just dfs for both tble and plt — amrrs
– amrrs, Commented Nov 9, 2017 at 7:02
Yes for the first question. As for the second, this is what I am stuck with. I really don't know how to pass the plot. I tried different methods and nothing worked so far. — user91
– user91, Commented Nov 9, 2017 at 7:05
Let me understand, you are already creating ggplot inside Identify_IP or you want to create one inside the reactive function in server.R? — amrrs
– amrrs, Commented Nov 9, 2017 at 7:10

micstr · Accepted Answer · 2017-11-09 14:14:19Z

I managed to get this working.

Note I used the internal data set iris and made a toy Identify_IP function as I do not have your code.

Note you still need to choose a file to trigger the events but it will ignore that file and use iris data.

Workaround I used [[1]] to get the table not dataOP()$tble

CODE

library(shiny)
library(ggplot2)

# source('InflectionP2.R', local = TRUE)
# MAKE TEST FUNCTION
Identify_IP <- function(mydata) {

  #shrink data
  tble <- head(mydata)

  plt <-  ggplot(data = head(mydata),
                 mapping = aes(y = Sepal.Length,
                               x = Petal.Length)) + geom_point()

  return(list(tble, plt))
}




runApp(
  list(
    ui = fluidPage(
      titlePanel("Upload your file"),
      sidebarLayout(
        sidebarPanel(
          fileInput('file1', 'Choose xls file',
                    accept = c(".XLS")),

          actionButton("btn", "Update Table"),
          actionButton("btn1", "Display Plot")

        ),

        mainPanel(

          tableOutput('what'),
          plotOutput('pl'))
      )

    )
    ,

    server = function(input, output, session){

      dataOP <- reactive({
        inFile <- input$file1
        if (is.null(input$file1))
          return(NULL)

        # ORIGINAL dfs <- Identify_IP(read.table(inFile$datapath))
        # using internal dataset for example
        dfs <- Identify_IP(iris)

        # ORIGINAL list(tble = dfs, plt = dfs)
        # lets just return your dfs, its already a list in code above
        return(dfs)
      })


      observeEvent(input$btn, output$what <-  renderTable({

        #print(dataOP()) # debug line that led to [[1]] idea
        # ORIGINAL  dataOP()$tble
        # just say first in list
        dataOP()[[1]]

        }))

      observeEvent(input$btn1, output$pl <- renderPlot({


        #ggplot(dataOP()$plt)
        # since already a plot just need to index it
        # I found [[2]] worked better than explicit dataOP()$plt
        pp <- dataOP()

        pp[[2]]

      }))             
    }))

RESULT

Voila!

It makes sense to me. It still doesn't work. I will modify my code above and display Identify_IP() and the ggplot it returns.

micstr · Accepted Answer · 2017-11-09 08:15:53Z

0

1) Try print (ggplot(dataOP()$plt))

Take a look at this answer I wrote.

2) Sorry its hard to interpret without your ggplot code bit and data. Given @amrrs questions can you try debug in your Shiny code with print() and str() temporary lines to see what your data is returning. i.e.

print(dataOP()$plt)
str(dataOP())

Worse case, try split your code in two. So Identify_IP code to do the data leg and then make a Print_IP with the ggplot code that just returns the plot. It might rule out your chart is not the problem.

3) Take a look at reactiveValues()

https://shiny.rstudio.com/reference/shiny/0.11/reactiveValues.html

It "bakes" a result that was reactive. The type coming out of your chart may be a reactive type not a chart type. Perhaps share any error messages you are getting.

edited Nov 9, 2017 at 8:15

answered Nov 9, 2017 at 6:26

micstr

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2 Comments

user91 Over a year ago

Not working. I'm wondering if I'm passing the objects correctly in the List inside reactive function. I think the problem is that I don't know how to pass the arguments.

micstr Over a year ago

MarJamil i think this answer may be very useful - stackoverflow.com/a/24899084/4606130. Inside your renderPlot() take dd <- dataOP()$plt do your p <- ggplots(dd etc) on dd and then print(p)

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