R Shiny problem to pass reactive input to another function after plotting - r

Question

I am new user of R Shiny and I have got a problem with passing reactive input to another function after plotting this reactive input.
In short, I want to create application which allow user to upload csv file, then choose x and y variables, plot these variables and then calculate area under curve of this plot. I could do everything except the last point. Plotting is fine, so I could pass reactive input to ggplot, but I could not pass it further to AUC function. Code line 126-129, at the end of coding. I know it is something very stupid which is missing, but now I am really stack. Tried different things, different wrong messages. Now it is: argument 1 is not a vector. I could run AUC is will make hard input of variables names such as AUC(data()$time, data()$response, method ="spline"), but I could not pass into AUC function user input for some reason.
Sorry for the stupid question.
Thank you for the help.
Here is the whole code.
library(shiny)
library(ggplot2)
library(dplyr)
library(tidyverse)
library(DescTools)
library(pROC)
library(shinythemes)
ui <- shinyUI(fluidPage(
titlePanel("Column Plot"),
tabsetPanel(
tabPanel("Upload File",
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('file1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv')),
tags$br(),
checkboxInput('header', 'Header', TRUE),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
';'),
radioButtons('quote', 'Quote',
c(None='',
'Double Quote'='"',
'Single Quote'="'"),
'"')
),
mainPanel(
tableOutput('contents')
)
)
),
tabPanel("Plot",
pageWithSidebar(
headerPanel('My Plot'),
sidebarPanel(
# "Empty inputs" - they will be updated after the data is uploaded
selectInput("xcol", "X Variable", ""),
selectInput("ycol", "Y Variable", "", selected = "")
),
mainPanel(
plotOutput("MyPlot")
)
),
######
h4("Area under curve"),
textOutput("AUC")
)
)
)
)
server <- shinyServer(function(input, output, session) {
# added "session" because updateSelectInput requires it
data <- reactive({
req(input$file1) ## ?req # require that the input is available
inFile <- input$file1
df <- read.csv(inFile$datapath, header = input$header, sep = input$sep,
quote = input$quote)
# Update inputs (you could create an observer with both updateSel...)
updateSelectInput(session, inputId = "xcol", label = "X Variable",
choices = names(df), selected = names(df))
updateSelectInput(session, inputId = "ycol", label = "Y Variable",
choices = names(df), selected = names(df)[2])
return(df)
})
output$contents <- renderTable({
data()
})
output$MyPlot <- renderPlot({
x <- req(input$xcol)
y <- req(input$ycol)
p <- ggplot(data(), aes_string(x = x, y = y)) + geom_point(color="blue", size =7)
plot(p)
############
# Here is the problem, I can not pass x and y to the AUC function to calculate area under curve
# for the user input
output$AUC <- renderText({
AUC <- AUC(data()$x, data()$y, method ="spline")
})
#######################
})
})
shinyApp(ui, server)

Answer 1

The problem is that you call the columns x and y in your function AOC but these columns are only defined in your renderPlot, not in the whole server.
Replacing x and y by input$xcol and input$ycol (and using [[ ]]) allows to compute the area under the curve.
Corrected example below:
library(shiny)
library(ggplot2)
library(dplyr)
library(tidyverse)
library(DescTools)
library(pROC)
library(shinythemes)
ui <- shinyUI(fluidPage(
titlePanel("Column Plot"),
tabsetPanel(
tabPanel("Upload File",
titlePanel("Uploading Files"),
sidebarLayout(
sidebarPanel(
fileInput('file1', 'Choose CSV File',
accept=c('text/csv',
'text/comma-separated-values,text/plain',
'.csv')),
tags$br(),
checkboxInput('header', 'Header', TRUE),
radioButtons('sep', 'Separator',
c(Comma=',',
Semicolon=';',
Tab='\t'),
';'),
radioButtons('quote', 'Quote',
c(None='',
'Double Quote'='"',
'Single Quote'="'"),
'"')
),
mainPanel(
tableOutput('contents')
)
)
),
tabPanel("Plot",
pageWithSidebar(
headerPanel('My Plot'),
sidebarPanel(
# "Empty inputs" - they will be updated after the data is uploaded
selectInput("xcol", "X Variable", ""),
selectInput("ycol", "Y Variable", "", selected = "")
),
mainPanel(
plotOutput("MyPlot")
)
),
######
h4("Area under curve"),
textOutput("AUC")
)
)
)
)
server <- shinyServer(function(input, output, session) {
# added "session" because updateSelectInput requires it
data <- reactive({
req(input$file1) ## ?req # require that the input is available
inFile <- input$file1
df <- read.csv(inFile$datapath, header = input$header, sep = input$sep,
quote = input$quote)
# Update inputs (you could create an observer with both updateSel...)
updateSelectInput(session, inputId = "xcol", label = "X Variable",
choices = names(df), selected = names(df))
updateSelectInput(session, inputId = "ycol", label = "Y Variable",
choices = names(df), selected = names(df)[2])
return(df)
})
output$contents <- renderTable({
data()
})
output$MyPlot <- renderPlot({
x <- req(input$xcol)
y <- req(input$ycol)
p <- ggplot(data(), aes_string(x = x, y = y)) + geom_point(color="blue", size =7)
plot(p)
############
# Here is the problem, I can not pass x and y to the AUC function to calculate area under curve
# for the user input
output$AUC <- renderText({
AUC(data()[[input$xcol]], data()[[input$ycol]], method ="spline")
})
#######################
})
})
shinyApp(ui, server)
Edit: you may have an error
Error: maximum number of subdivisions reached
but I suppose this is due to the function AOC.