Rename variable based on textInput value in Shiny

Question

I want to update variable names in a dashboard based on value of textInput. I have prepared a reproducible example using mtcars dataset. I have commented out the areas where I was trying to rename, but did not work.

library(shiny)
library(dplyr)

ui <- fluidPage(
  fluidRow(
    column(
      4, 
      selectInput("x", "select x variable", colnames(mtcars), "mpg"),
      selectInput("y", "select y variable", colnames(mtcars), "wt"),
      br(),
      uiOutput("xxx"),
      uiOutput("yyy")
    ),
    column(
      8,
      verbatimTextOutput("summary")
    )
  )
)

server <- function(input, output, session) {

  output$xxx <- renderUI({
    textInput("xlab", "Rename x variable", value = input$x)
  })

  output$yyy <- renderUI({
    textInput("ylab", "Rename y variable", value = input$y)
  })

  # df <- reactive({
  #   select(mtcars, input$x, input$y) %>%
  #     rename(input$xlab = input$x, input$ylab = input$y)
  # })

  output$summary <- renderPrint({
    select(mtcars, input$x, input$y) %>% summary()
    # df() %>% summary()
  })
}

shinyApp(ui, server)

score 1 · Accepted Answer · edited Aug 22 '18 at 22:09

You can use colnames() function to name the columns after your reactive datframe is generated. I added a req() statement in renderPrint() which avoids error when the app is loading.

library(shiny)
library(dplyr)

ui <- fluidPage(
  fluidRow(
    column(
      4, 
      selectInput("x", "select x variable", colnames(mtcars), "mpg"),
      selectInput("y", "select y variable", colnames(mtcars), "wt"),
      br(),
      uiOutput("xxx"),
      uiOutput("yyy")
    ),
    column(
      8,
      verbatimTextOutput("summary")
    )
  )
)

server <- function(input, output, session) {

  output$xxx <- renderUI({
    textInput("xlab", "Rename x variable", value = input$x)
  })

  output$yyy <- renderUI({
    textInput("ylab", "Rename y variable", value = input$y)
  })

  df <- reactive({
    df.selected <- select(mtcars, input$x, input$y) 
    #colnames(df.selected) <- c(input$xlab, input$ylab)

    # Edit - Keep original column names if textInputs are empty 
    # func.for.colnames <- function(){ 
    #   if (!isTruthy(input$xlab) | !isTruthy(input$xlab)){  
    #     return(c(input$x, input$y))
    #   }
    #   
    #   else {
    #     return(c(input$xlab, input$ylab))
    #   }}
    # 
    # colnames(df.selected) <- func.for.colnames()

    # Edit2 - Above function is too complicated. The following works flawlessly
    if(isTruthy(input$xlab)) {
      colnames(df.selected)[1] <- input$xlab
    }
    if(isTruthy(input$ylab)) {
      colnames(df.selected)[2] <- input$ylab
    }

    df.selected

  })

  output$summary <- renderPrint({
    # req(input$xlab) # Unnecessary
    summary(df())
  })
}

shinyApp(ui, server)

Do you know how to keep verbatimTextOutput() with old variable names if textInput are empty? I am playing with if(is.null(input$xlab)) ... but can't crack it — Masood Sadat, Aug 22 '18 at 19:01
You can use isTruthy() to check if textInputs are empty. See edit. — Vishesh Shrivastav, Aug 22 '18 at 19:41
I was missing `isTruthy()`! I replaced the function and it works perfectly — Masood Sadat, Aug 22 '18 at 22:07
Great! I see you edited the code according to your requirements. That's cool, please mark the answer as correct. — Vishesh Shrivastav, Aug 22 '18 at 22:11

Rename variable based on textInput value in Shiny

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