How to update models within shiny if new data is provided?

[WIK]

Hello,

I want to create a shiny page with a model (already exists). Yet, additional to the "old" models implemented I would like the user to be able to upload new data and combine it with the old data. Based on this new data I want to create a new model and display, this discarding the old model. If the user does not upload new data I want the old model and data to be displayed. In short if(new){new model + new plot}else{old model + old plot}. However, the (example) code below only displays the plot if new data is provided, but not the old model if no data is provided. I am not able to figure out how to incorporate this into the reactive environment. Does anyone know how to incorporate this in shiny?

Thank you in advance,

library(shiny)

#stored in app folder as model1
x <- 1:100
set.seed(123)
y1<- 1.5*x+rnorm(100,0,50)
old <- data.frame(x,y1)
model1 <- lm(y1~.,data = old)

#Uploaded as new data
#set.seed(1)
#y2 <- 1.43*x+rnorm(100,0,40)
#new <- data.frame(x,y2)
#write.csv(new,file = "new.csv",row.names = F)

#shiny app
ui <- fluidPage(

    titlePanel("Stuff"),

    sidebarPanel(fileInput("file1", "Upload file y~x.",
                           multiple = FALSE,
                           accept = c("text/csv",
                                      "text/comma-separated-values,text/plain",
                                      ".csv"))),

        mainPanel(
           plotOutput("Plot")
        )
    )

server <- function(input, output, session) {
    
    newdata <- reactive({
    
         req(input$file1)
        
         new <- input$file1
        
         if(is.null(new)){return(old)}else{

         new <- as.data.frame(read.csv(input$file1$datapath, stringsAsFactors = TRUE))
    
         colnames(new)<-c("x","y1")
         
         return(rbind(old, new))}})
    

    output$Plot <- renderPlot({
        
        new <- newdata()
        
        if(!is.null(new)){
        
        plot(new)
        abline(lm(new$y1~.,data=new))}else{
            plot(old)
            abline(model1)}
})
    
}

shinyApp(ui = ui, server = server)

[nirgrahamuk]

the file input aspect seems a distraction from the main question of how to approach this, so I removed it from the reprex.

library(shiny)
library(tidyverse)

#stored in app folder as model1
x <- 1:100
set.seed(123)
y1<- 1.5*x+rnorm(100,0,50)
old <- data.frame(x,y1)
model1 <- lm(y1~.,data = old)

#Uploaded as new data
set.seed(1)
y2 <- 1.43*x+rnorm(100,0,40)
new <- data.frame(x,y2)
#write.csv(new,file = "new.csv",row.names = F)

#shiny app
ui <- fluidPage(
   
   titlePanel("Stuff"),
   
   sidebarPanel(checkboxInput("newloadtgl",label="simulate new file loaded")),
   
   mainPanel(
      plotOutput("Plot")
   )
)

server <- function(input, output, session) {
   
   newdata <- reactiveVal(NULL)
   
   observeEvent(input$newloadtgl,
                {
                   if(input$newloadtgl){
                      newdata({
                         rbind(old,new %>% setNames(c("x","y1")))
                      })
                   } else
                      newdata(NULL)
                })

   
   
   output$Plot <- renderPlot({
      
      new1 <- newdata()
      
      if(!is.null(new1)){
         
         plot(new1)
         abline(lm(y1~.,data=new1))}else{
            plot(old)
            abline(model1)}
   })
   
}

shinyApp(ui = ui, server = server)

[WIK]

[quote="nirgrahamuk, post:2, topic:105869"]

I seem to get the following error. Also, if no file is provided it will return an error since there is no new data to bind? Or, am I wrong?

Warning: Error in <-: names() applied to a non-vector
  84: setNames
  83: function_list[[k]]
  81: freduce
  80: _fseq
  79: eval
  78: eval
  76: %>%
  72: observeEventHandler [C:...app.R#40]
   1: runApp

Minor edit, it works if reactiveVal() and observeEvent()
are replaced by

    newdata <- reactive({
        inFile <- input$file1
        if (is.null(inFile)){return(NULL)}else{
        new <- as.data.frame(read.csv(input$file1$datapath, stringsAsFactors = TRUE))
        colnames(new) <- c("x","y1")
        return(rbind(old, new))}
    })

The app directly creates the new model over the old then, the issue is you cannot go back to the old model, unless you refresh the page.

[nirgrahamuk]

@WIK

I seem to get the following error.

not when you run the code I supplied as I supplied it, surely ?

[WIK]

You are right, not if I run the code provided. But your example gave me some difficulties incorporating it in the code, although it gave me information to look for some other solutions +1. Coding jargon is often a difficult topic searching for solution without a coding background.

[nirgrahamuk]

I can recommend https://mastering-shiny.org/ as a great reference