R,Shiny: Using selectInput() selection to create data frame

Question

This seems like it should be trivial but I'm obviously missing something. I'd like to have the selection from a selectInput() be used to create a data frame. The selectInput() produces a character output that doesn't seem to work as an input for creating a data frame. My ui.R and server.R code is below. The df<-data.frame(input$select, header=TRUE) line doesn't produce the expected output. Thanks in advance for your assistance.

ui.R

library(shiny)

shinyUI(

  # Use a fluid Bootstrap layout
  fluidPage(    

    # Give the page a title
    titlePanel("Select Test Dataset"),

    # Generate a row with a sidebar
    sidebarLayout(      

      # Define the sidebar with one input
      sidebarPanel(
        selectInput("select", "Test Dataset", 
                    choices= list("Model Year 2011" = 'cars2011', "Model Year 2012" = 'cars2012'),selected='cars2011')

      ),

      # mainPanel Output
      mainPanel(
        verbatimTextOutput("value"),
        verbatimTextOutput("type"),
        dataTableOutput(outputId="data")
      )

    )
  )
)

server.R

library(AppliedPredictiveModeling)
data(FuelEconomy)



shinyServer(function(input, output) {

  output$value <- renderPrint({ input$select })
  output$type <- renderPrint({class(input$select)})

  output$data <- reactive({
    df <- data.frame(input$select, header=TRUE)
    head(df)
  })




})

Quinn Weber · Accepted Answer · 2015-05-17 23:31:54Z

1

You should use shiny::renderDataTable instead of shiny::reactive when defining output$data.

output$data <- renderDataTable({
    df <- data.frame(input$select, header=TRUE)
    head(df)
})

answered May 17, 2015 at 23:31

Quinn Weber

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4 Comments

maRtin Over a year ago

is this code working for you? I tested this solution but I still wasnt able to see any output.

R Estabrook Over a year ago

The answer renders a data table, but doesn't display the correct data. The problem is in passing a character string to data.frame. The following R code illustrates the problem: >chr <- "cars2011" >class(chr) [1] "character" >df<-data.frame(chr,head=TRUE) >head(df) chr head 1 data2011 TRUE

Quinn Weber Over a year ago

Thanks for clarifying. What would you like the output to look like?

R Estabrook Over a year ago

Quinn, The answer I posted provides the desired output. Thank you for your suggestion regarding the use of renderDataTable: it is obviously the preferred method for displaying data and I will use it in my application.

R Estabrook · Accepted Answer · 2015-05-18 14:26:26Z

1

Converting the character string to a data frame name using a switch statement seems to work.

In server.R inserting:

dataset <- reactive({ switch(input$select, "cars2011" = cars2011, "cars2012" = cars 2012) })

and then using head(dataset()) to output data provides the desired result.

answered May 18, 2015 at 14:26

R Estabrook

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