Shiny - Changing Variables on a Plot Based on User Input

Question

I have a data set that looks like the following:

Win    Gender    Score (1-4)    Weight     SHE
1      F         2              140        Y
0      M         3              155        Y
1      M         4              134        N

I am creating a Shiny App that will create side by side bar charts for the rows that belong to the different scores (4 groups). I want the user to be able to select the variable that will be on the x-axis (either Win, Gender of SHE), and have the charts update to reflect the counts of that variable within each group.

I have tried the following code in server.R:

shinyServer(function(input, output){
     output$plotOne <- renderPlot({
ggplot(data=GroupOne, aes(x=input$var))+geom_bar(stat='bin')
})
})

'var' is the name that I have specified for the variable the user selects based on the radio button input in ui.R. The error message I am getting is that input is not found.

I have also tried the above code, but with

histogram(~input$var, data=GroupOne).

This resulted in errors about negative length vectors and other things.

which is empty for this specific example. does the problem persists for score==2? — Yevgeny Tkach
– Yevgeny Tkach, Commented Jun 2, 2015 at 14:03
The problem persists for all of the groups. The data set is larger, I just included the first three rows as an example, but all groups contain multiple entries. — Megan
– Megan, Commented Jun 2, 2015 at 14:14
Can you say explicitly what the error says? The "other things" could be significant. And when you say that it says "input is not found," do you mean the input to the function, or the object "input"? — Colin Robinson
– Colin Robinson, Commented Jun 2, 2015 at 17:48

Renel Chesak · Accepted Answer · 2017-03-12 01:40:53Z

2

Try using a reactive function to tie the input into your data frame:

server <- function(input, output) {

  data <- reactive({
if ( "Win" %in% input$var) return(your_data_frame$Win)
if ( "Gender" %in% input$var) return(your_data_frame$Gender)
if ( "Score" %in% input$var) return(your_data_frame$Score)
if ( "Weight" %in% input$var) return(your_data_frame$Weight)
if ( "SHE" %in% input$var) return(your_data_frame$SHE)
  })

  output$plotOne <- renderPlot({
ggplot(data=GroupOne, aes(x=data()))+geom_bar(stat='bin')
  })
}

answered Mar 12, 2017 at 1:40

Renel Chesak

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