Building a model with a reactive formula in shiny using selected inputs-CodePudding

I have a problem with object 'input' not found in formula. When I try to use input of selectInput, it throws me this error. T tried everything, but nothing helps. Can someone help me with this issue please ?

SERVER

idk = reactive({
     id = sample(2, nrow(df1()), replace = TRUE, prob = c(input$slider, 1-input$slider))
     id
   })
   
   
   output$dev <- renderText({ 
     paste0("Training part is: ",input$slider) 
   })
   
   output$dev2 <- renderText({ 
     paste0("Testing part is: ",1-input$slider) 
   })
   
   train_datas = reactive({
     train_data = df1()[idk() == 1, ]
     train_data
   })
   
   test_datas = reactive({
     test_data = df1()[idk() == 2, ]
     test_data
   })

outVar = reactive({
     mydata = test_datas()
     names(mydata)
   })
   
   
   observe({
     updateSelectInput(session, "columns1",
                       choices = outVar()
     )})
   
   observe({
     updateSelectInput(session, "columns2",
                       choices = outVar()
     )})
   
   observe({
     updateSelectInput(session, "columns3",
                       choices = outVar()
     )})
   
   observe({
     updateSelectInput(session, "columns4",
                       choices = outVar()
     )})

   tree = reactive({
     mydata = train_datas()
     tree2 = ctree(formula = input$columns1 ~ input$columns2   input$columns3   input$columns4, data = mydata)
     tree2
   })
   
   output$try <- renderPrint({
     return(tree())
     
   })

 tabPanel("Data prepare",
                      sidebarLayout(
                        sidebarPanel( 
                          numericInput("slider", "Train data (0-1)", 1,
                                       0.1, 1, 0.05),
                          textOutput("dev"),
                          textOutput("dev2"),
                          tags$hr(),
                          textOutput("dev3"),
                          textOutput("dev4"),
                          tags$hr(),
                          selectInput('columns1', 'Columns1', ""),
                          selectInput('columns2', 'Columns2', ""),
                          selectInput('columns3', 'Columns3', ""),
                          selectInput('columns4', 'Columns4', "")
                         
                        ),
                        
                        mainPanel(verbatimTextOutput("try"))
                    ))

I add whole code whichh is connect to my question. What I need is get input value of last four select inputs - column1, column2, column3, column4.

CodePudding user response：

This is how to update choices of selectInput according to the current value of the available variables of the input data frame (outVar in your case). Then, the selected choices will be used as response and predictor variables in a reactive model:

library(shiny)

ui <- fluidPage(
  selectInput("response", "response", ""),
  selectInput("predictor", "predictor", ""),
  verbatimTextOutput("model")
)

server <- function(session, input, output) {
  # Example data
  data <- reactive(iris)

  variables <- reactive(colnames(data()))

  formula <- reactive({
    paste0(input$response, "~", input$predictor) %>% as.formula()
  })

  # dummy model using reactive formula
  model <- reactive({
    lm(formula = formula(), data = data())
  })

  # Display sth about the reactive model
  output$model <- renderText({
    model() %>%
      coefficients() %>%
      as.character()
  })

  observeEvent(
    eventExpr = variables,
    handlerExpr = {
      updateSelectInput(session, "response", choices = variables(), selected = variables()[[1]])
      updateSelectInput(session, "predictor", choices = variables(), selected = variables()[[2]])
    }
  )
}

shinyApp(ui, server)