How to replace values of a columns of CSV in R shiny-CodePudding

The code below is written in R shiny and currently reads data from the 'mtcars' database. This app was made to replace the specific data in a column., It has options such as 'Column to search' for selecting columns, "replace" and "By" for replacing values that the user specifies in the 'Replace' field. It is now working perfectly.

But what I really want is to use 'Browse' to upload my own csv data and perform the same operations as 'Replace' and 'BY'. How to accomplish this?

Expected result:

How can values be replaced? (from old to new values). as an example How should I modify the value 100 to 500 in the 'range' column by referencing the column name in the 'select column' from the below csv data?

current csv:

ID  Type  Category    Range
21  A1     B1          100
22  C1     D1          200
23  E1     F1          300

Expected CSV results:

ID  Type  Category    Range
21  A1     B1          500
22  C1     D1          200
23  E1     F1          300

app.R

library(shiny)
library(DT)
library(dplyr)

ui <- fluidPage(
   sidebarLayout(
      sidebarPanel(
         fileInput("file1", "Choose CSV File", accept = ".csv"),
         selectInput("col", "Column to search:", names(mtcars), names(mtcars)[1]),
         textInput("old", "Replace:"),
         textInput("new", "By:"),
         actionButton("replace", "Replace!"),
      ),
      mainPanel(
         DTOutput("table1")
      )
   )
)

server <- function(input, output, session) {
   my_data <- reactiveVal(mtcars)
   
   observeEvent(input$replace, {
      req(input$col)
      dat <- my_data()
      traf <- if (is.numeric(dat[[input$col]])) as.numeric else identity
      my_data(dat %>%
                 mutate(!!rlang::sym(input$col) := 
                           replace(!!rlang::sym(input$col),
                                   as.character(!!rlang::sym(input$col)) == input$old,
                                   input$new) %>% 
                           traf()))
   })
   
   output$table1 <- renderDT(
      my_data()
   )
}

shinyApp(ui, server)

CodePudding user response：

You just need to add the fileUploader logic to fill my_data accordingly:

ui <- fluidPage(
   sidebarLayout(
      sidebarPanel(
         fileInput("file1", "Choose CSV File", accept = ".csv"),
         checkboxInput("header", "Header", TRUE),
         selectInput("col", "Column to search:", NULL),
         textInput("old", "Replace:"),
         textInput("new", "By:"),
         actionButton("replace", "Replace!"),
      ),
      mainPanel(
         DTOutput("table1")
      )
   )
)

server <- function(input, output, session) {
   my_data <- reactiveVal(NULL)
   
   observeEvent(input$file1, {
      file <- input$file1
      ext <- tools::file_ext(file$datapath)
      req(file)
      validate(need(ext == "csv", "Please upload a csv file"))
      my_data(read.csv(file$datapath, header = input$header))
      updateSelectInput(session, "col", choices = names(my_data()))
   })
   
   observeEvent(input$replace, {
      req(input$col)
      dat <- req(my_data())
      traf <- if (is.numeric(dat[[input$col]])) as.numeric else identity
      my_data(dat %>%
                 mutate(!!rlang::sym(input$col) := 
                           replace(!!rlang::sym(input$col),
                                   as.character(!!rlang::sym(input$col)) == input$old,
                                   input$new) %>% 
                           traf()))
   })
   
   output$table1 <- renderDT(
      req(my_data())
   )
}