CODEWITHSUNDEEP
rshinyreactiver-leaflet
Luke
Luke

Reputation: 1

Referencing a data table output for further actions

I have the following app to upload and display a datafile:

library(shiny)
library(DT)
library(leaflet)

ui <- fluidPage(

  titlePanel('SNP_Review'),
  sidebarLayout(
    sidebarPanel(
    fileInput('target_upload', 'Choose file to upload', accept = c(
      'text/csv',
      'text/comma-separated-values',
      '.csv'
    )),
    ),
    
  mainPanel(
    tabsetPanel(
      type = "tabs",
      tabPanel('Samples_table', DT::dataTableOutput("sample_table")),
      tabPanel('Samples_map', leafletOutput("sample_map"))
      )
    )
  )
)

server <- function(input, output) {
  
  df_products_upload <- reactive({
    inFile <- input$target_upload
    if (is.null(inFile))
      return(NULL)
    df <- read.csv(inFile$datapath, header = TRUE,sep = input$separator)
    return(df)
  })
  
  output$sample_table <- DT::renderDataTable({
    df <- df_products_upload()
    DT::datatable(df)
    
  })
  
  table_data <- reactive({
    
  })
  
  output$sample_map <- renderLeaflet({
    leaflet(data = table_data()) %>%
      addProviderTiles(providers$OpenStreetMap.DE) %>%
      addMarkers(lng = ~Longitude, lat = ~Latitude)
     
  })  
}
 
shinyApp(ui = ui, server = server)

It prints out my data in a table. In the next step, I would like to show the GPS-data of the table on a map with leaflet. How can I define the reactive table_data() function after the table output to use the data in the map and in possible further operations? The table looks like this:

    Name_ID Population  Latitude Longitude
2 F6537_S01    Finland 60,745411 25,468228
3 N0484_S13     Norway 59,480365  7,920383
4 N0485_S25     Norway 60,925393  10,61182
5 N0486_S37     Norway 62,903547  9,824941
6 N0487_S49     Norway  61,78245 11,918215

Upvotes: 0

Views: 460

Answers (1)

Bertil Baron
Bertil Baron

Reputation: 5003

This is exactly what reactive functions are for. Reactive statements are lazy, that means they are only evaluated once until the are labeled invalid, which happens when a reactive statement within(such as input or another reactive function) changes value. As long as a reactive statement is calculated and not labeled invalide shiny will handle it as an object.

Therefor I would jus change your server code like this

server <- function(input, output) {
  
  df_products_upload <- reactive({
    inFile <- input$target_upload
    if (is.null(inFile))
      return(NULL)
    df <- read.csv(inFile$datapath, header = TRUE,sep = input$separator)
    return(df)
  })
  
  output$sample_table <- DT::renderDataTable({
    df <- df_products_upload()
    DT::datatable(df)
    
  })
  
  output$sample_map <- renderLeaflet({
    leaflet(data = df_products_upload()) %>%
      addProviderTiles(providers$OpenStreetMap.DE) %>%
      addMarkers(lng = ~Longitude, lat = ~Latitude)
     
  })  
}

Upvotes: 1

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