Resize party package ctree plot using a R shiny slider

How do you resize the output of a ctree using reactive inputs in R shiny?

My attempt

ui:

rm(list=ls())

library(shiny)
library(party)

# Define the overall UI
shinyUI(fluidPage(
  titlePanel("Unbiased Recursive Partitioning"),

  sidebarLayout(
    sidebarPanel(   
      actionButton("go", "Plot URP-Ctree")
    ),

    mainPanel(
      # Create a new row for the URP plot.
      sliderInput("sliderWidth", label = "", min = 10, max = 3000, value = 1000),
      sliderInput("sliderHeight", label = "", min = 10, max = 3000, value = 1000),
      plotOutput("plot")
    ))
  )
)

server:

# server.R
rm(list=ls())

CCS<-c(41, 45, 50, 50, 38, 42, 50, 43, 37, 22, 42, 48, 47, 48, 50, 47, 41, 50, 45, 45, 39, 45, 46, 48, 50, 47, 50, 21, 48, 50, 48, 48, 48, 46, 36, 38, 50, 39, 44, 44, 50, 49, 40, 48, 48, 45, 39, 40, 44, 39, 40, 44, 42, 39, 49, 50, 50, 48, 48, 47, 48, 47, 44, 41, 50, 47, 50, 41, 50, 44, 47, 50, 24, 40, 43, 37, 44, 32, 43, 42, 44, 38, 42, 45, 50, 47, 46, 43,
       37, 47, 37, 45, 41, 50, 42, 32, 43, 48, 45, 45, 28, 44,38, 41, 45, 48, 48, 47 ,49, 16, 45, 50, 47, 50, 43, 49, 50)

X1.2Weeks<-c(NA,NA,NA,NA,NA,1,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,2,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,NA,NA,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,1,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,1,1,2,2,1,2,2,2)
X2.2Weeks<-c(NA,NA,NA,NA,NA,NA,2,2,2,NA,NA,2,2,2,2,2,2,NA,2,2,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,NA,NA,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,1,2,2,2,2,2,2,2)
X3.2Weeks<-c(NA,35,40,NA,10,NA,31,NA,14,NA,NA,15,17,NA,NA,16,10,15,14,39,17,35,14,14,22,10,15,0,34,23,13,35,32,2,14,10,14,10,10,10,40,10,13,13,10,10,10,13,13,25,10,35,NA,13,NA,10,40,0,0,20,40,10,14,40,10,10,10,10,13,10,8,NA,NA,14,NA,10,28,10,10,15,15,16,10,10,35,16,NA,NA,NA,NA,30,19,14,30,10,10,8,10,21,10,10,35,15,34,10,39,NA,10,10,6,16,10,10,10,10,34,10)
X4.2Weeks<-c(NA,NA,511,NA,NA,NA,NA,NA,849,NA,NA,NA,NA,1324,1181,832,1005,166,204,1253,529,317,294,NA,514,801,534,1319,272,315,572,96,666,236,842,980,290,843,904,528,27,366,540,560,659,107,63,20,1184,1052,214,46,139,310,872,891,651,687,434,1115,1289,455,764,938,1188,105,757,719,1236,982,710,NA,NA,632,NA,546,747,941,1257,99,133,61,249,NA,NA,1080,NA,645,19,107,486,1198,276,777,738,1073,539,1096,686,505,104,5,55,553,1023,1333,NA,NA,969,691,1227,1059,358,991,1019,NA,1216)
x4.3Weeks<-c(NA,NA,511,NA,NA,NA,NA,NA,0,NA,NA,72,NA,1324,1181,832,1005,166,204,1253,529,317,294,NA,514,801,534,1319,272,315,572,96,666,236,842,980,290,843,904,528,27,366,540,560,659,107,63,20,1184,1052,214,46,139,310,872,891,651,687,434,1115,1289,455,764,938,1188,105,757,719,1236,982,710,NA,NA,632,NA,546,747,941,1257,99,133,61,249,NA,NA,1080,NA,645,19,107,486,1198,276,777,738,1073,539,1096,686,505,104,5,55,553,1023,1333,NA,NA,969,691,1227,1059,358,991,1019,NA,1216)

dat<-as.data.frame(cbind(CCS,X1.2Weeks,X2.2Weeks,X3.2Weeks,X4.2Weeks,x4.3Weeks))


library(shiny)
library(party)

shinyServer(function(input, output, clientData, session) {


  sliderWidth<-reactive({
    as.integer(input$sliderWidth)
  })

  sliderHeight<-reactive({
    as.integer(input$sliderHeight)
  })


  # Construct URP-Ctree
  output$plot <- renderPlot({ 
    if(input$go==0){
      return()
    }
    else {
      isolate({
        an<-"CCS"
        # Only columns with "2Weeks" as part of their title are selected as predictors
        control_preds<-"2Weeks"

        preds<-names(dat)[grepl(paste(control_preds),names(dat))]
        datSubset<-subset(dat,dat[,an]!="NA")  
        anchor <- datSubset[,an]
        predictors <- datSubset[,preds]
        urp<-ctree(anchor~., data=data.frame(anchor,predictors))
        plot(urp) 
      })
    }
  },height = 500, width = 500)
  # },height = sliderHeight(), width = sliderWidth())<-- Causes error
})

Running the above code you should get a ctree after you click the button. However the sliders don't do anything. If you change the height and width arguments of renderPlot to something other than 500 the size of the plot does change. How do I bring height and width under the control of the sliders?

When I try to run server with height = sliderHeight(), width = sliderWidth() in the last line I get:

Error in .getReactiveEnvironment()$currentContext() : 
  Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)

And I'm confused since I used reactive expressions.

Solution

Two months on and I pay my best friend $500 bucks to solve this. Code below and I have no idea why a reactive expression inside a reactive expression solves this. ui stays unchanged.

# server.R
rm(list=ls())

CCS<-c(41, 45, 50, 50, 38, 42, 50, 43, 37, 22, 42, 48, 47, 48, 50, 47, 41, 50, 45, 45, 39, 45, 46, 48, 50, 47, 50, 21, 48, 50, 48, 48, 48, 46, 36, 38, 50, 39, 44, 44, 50, 49, 40, 48, 48, 45, 39, 40, 44, 39, 40, 44, 42, 39, 49, 50, 50, 48, 48, 47, 48, 47, 44, 41, 50, 47, 50, 41, 50, 44, 47, 50, 24, 40, 43, 37, 44, 32, 43, 42, 44, 38, 42, 45, 50, 47, 46, 43,
       37, 47, 37, 45, 41, 50, 42, 32, 43, 48, 45, 45, 28, 44,38, 41, 45, 48, 48, 47 ,49, 16, 45, 50, 47, 50, 43, 49, 50)

X1.2Weeks<-c(NA,NA,NA,NA,NA,1,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,2,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,NA,NA,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,1,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,1,1,2,2,1,2,2,2)
X2.2Weeks<-c(NA,NA,NA,NA,NA,NA,2,2,2,NA,NA,2,2,2,2,2,2,NA,2,2,2,2,2,NA,2,2,2,2,2,2,2,NA,NA,NA,NA,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,NA,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,1,2,2,2,2,2,2,1,2,2,2,2,2,2,2)
X3.2Weeks<-c(NA,35,40,NA,10,NA,31,NA,14,NA,NA,15,17,NA,NA,16,10,15,14,39,17,35,14,14,22,10,15,0,34,23,13,35,32,2,14,10,14,10,10,10,40,10,13,13,10,10,10,13,13,25,10,35,NA,13,NA,10,40,0,0,20,40,10,14,40,10,10,10,10,13,10,8,NA,NA,14,NA,10,28,10,10,15,15,16,10,10,35,16,NA,NA,NA,NA,30,19,14,30,10,10,8,10,21,10,10,35,15,34,10,39,NA,10,10,6,16,10,10,10,10,34,10)
X4.2Weeks<-c(NA,NA,511,NA,NA,NA,NA,NA,849,NA,NA,NA,NA,1324,1181,832,1005,166,204,1253,529,317,294,NA,514,801,534,1319,272,315,572,96,666,236,842,980,290,843,904,528,27,366,540,560,659,107,63,20,1184,1052,214,46,139,310,872,891,651,687,434,1115,1289,455,764,938,1188,105,757,719,1236,982,710,NA,NA,632,NA,546,747,941,1257,99,133,61,249,NA,NA,1080,NA,645,19,107,486,1198,276,777,738,1073,539,1096,686,505,104,5,55,553,1023,1333,NA,NA,969,691,1227,1059,358,991,1019,NA,1216)
x4.3Weeks<-c(NA,NA,511,NA,NA,NA,NA,NA,0,NA,NA,72,NA,1324,1181,832,1005,166,204,1253,529,317,294,NA,514,801,534,1319,272,315,572,96,666,236,842,980,290,843,904,528,27,366,540,560,659,107,63,20,1184,1052,214,46,139,310,872,891,651,687,434,1115,1289,455,764,938,1188,105,757,719,1236,982,710,NA,NA,632,NA,546,747,941,1257,99,133,61,249,NA,NA,1080,NA,645,19,107,486,1198,276,777,738,1073,539,1096,686,505,104,5,55,553,1023,1333,NA,NA,969,691,1227,1059,358,991,1019,NA,1216)

dat<-as.data.frame(cbind(CCS,X1.2Weeks,X2.2Weeks,X3.2Weeks,X4.2Weeks,x4.3Weeks))


library(shiny)
library(party)

shinyServer(function(input, output, clientData, session) {


  sliderWidth<-reactive({
    as.integer(input$sliderWidth)
  })

  sliderHeight<-reactive({
    as.integer(input$sliderHeight)
  })


  # Construct URP-Ctree
  output$plot <- renderPlot({ 
    if(input$go==0){
      return()
    }
    else {
      isolate({
        an<-"CCS"
        # Only columns with "2Weeks" as part of their title are selected as predictors
        control_preds<-"2Weeks"

        preds<-names(dat)[grepl(paste(control_preds),names(dat))]
        datSubset<-subset(dat,dat[,an]!="NA")  
        anchor <- datSubset[,an]
        predictors <- datSubset[,preds]
        urp<-ctree(anchor~., data=data.frame(anchor,predictors))
        plot(urp) 
      })
    }
  }, height = reactive({sliderHeight()}), width = reactive({sliderWidth()}))
})

You can see in the width and height parameters above all that was needed was for my reactive call to itself be inside a reactive expression.