Append data to existing dataframe in R

Question

Hi Is there a way to append data to existing data in R. For example below application has dataframe populated based on user values , but right now, it is only creating new row and not appending.

Can we append this dataframe. I tried using reactive values as well. But did not work. Is there a way to achieve this?

library(shiny)
library(tidyr)
library(dplyr)
library(purrr)

ui <- basicPage(
  
  fluidRow(
    column(
      width = 6,
      textInput('a', 'Text A',"a1"),
      textInput('b', 'Text B',"b1"),
      textInput('c', 'Text A',"c1"),
      textInput('d', 'Text B',"d1"),
      textInput('e', 'Text A',"e1"),
      textInput('f', 'Text B',"f1"),
      uiOutput('f1')
    ),
    column(
      width = 6,
      tags$p(tags$span(id = "valueA", "")),
      tags$script(
        "$(document).on('shiny:inputchanged', function(event) {
          if (event.name === 'a') {
            $('#valueA').text(event.value);
          }
        });
        "
      )
      ,tableOutput('show_inputs')
    )
  )
)

server <- shinyServer(function(input, output, session){
  
  output$f1 <- renderUI({
    if(input$a == "a2"){
      textInput('z', 'Text B',"z1")
    } else {
      NULL
    }
  })
  
  AllInputs <- reactive({
    x <- reactiveValuesToList(input)
    # print(x)
    # data.frame(
    #   names = names(x),
    #   values = paste0(unlist(x, use.names = FALSE), Sys.time())
    # )
    
    tibble(
      key = names(x),
      data = x
    ) %>% 
      mutate(data = map(data, as.character)) %>% 
      unnest(data)
  })
  
  # observe({
  #   if(file.exists("file.csv")){
  #     write.table(AllInputs(), "file.csv", sep = ",", col.names = F, append = T, row.names = F)
  #   } else {
  #     write.csv(AllInputs(), "file.csv", sep = ",", row.names = F)
  #   }
  #   
  # })
  
  output$show_inputs <- renderTable({
    
    t(AllInputs())
  })
})
shinyApp(ui = ui, server = server)

thothal · Accepted Answer · 2022-05-10 07:11:11Z

1

You need to maintain a reactiveVal which holds your rows and to which you append on change:

library(shiny)
library(tidyr)
library(dplyr)
library(purrr)

ui <- basicPage(
   
   fluidRow(
      column(
         width = 6,
         textInput("a", "Text A","a1"),
         textInput("b", "Text B","b1"),
         textInput("c", "Text A","c1"),
         textInput("d", "Text B","d1"),
         textInput("e", "Text A","e1"),
         textInput("f", "Text B","f1"),
         uiOutput("f1")
      ),
      column(
         width = 6,
         tags$p(tags$span(id = "valueA", "")),
         tags$script(
            "$(document).on('shiny:inputchanged', function(event) {
                if (event.name === 'a') {
                   $('#valueA').text(event.value);
                }
             });"
      ), 
      tableOutput("show_inputs")
    )
  )
)

server <- shinyServer(function(input, output, session){
  
  my_data <- reactiveVal(list(character(0)) %>% 
                            rep(7) %>% 
                            set_names(letters[c(1:6, 26)]) %>% 
                            as_tibble())

  output$f1 <- renderUI({
    if(input$a == "a2"){
      textInput("z", "Text B", "z1")
    } else {
      NULL
    }
  })

  observe({
    new_row <- reactiveValuesToList(input)
    dat <- isolate(my_data())
    my_data(bind_rows(dat, new_row))
   })
  
  output$show_inputs <- renderTable({
    req(my_data())
  })
  
})

shinyApp(ui = ui, server = server)

Please note that you will need some extra logic to avoid that the dynamic input$f1 still holds text if you change the value in input$a1.

answered May 10, 2022 at 7:11

thothal

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5 Comments

manu p Over a year ago

Perfec thanks. Yeah Your right... How do we change the logic so that when input$a1 to any value other than 'a2', it should not show??? You know?

manu p Over a year ago

Also I see you have made column names static. Can we not make it dynamic? Like what if we have 20 more textinputs?

thothal Over a year ago

Well, I would initialize my_data with NULL and create the tibble in the observer.

manu p Over a year ago

Can you make a sample please?

manu p Over a year ago

i did try. but no luck. Can you help ?

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