Return dataframe of click coordinates

Question

I want to simply click on my plot, and have it return a data.frame to R listing the coordinates clicked. I've tried this:

library(shiny)
ui <- basicPage(
  plotOutput("plot1", click = "plot_click"),
  verbatimTextOutput("info")
)
server <- function(input, output) {
  output$plot1 <- renderPlot({
    plot(mtcars$wt, mtcars$mpg)
  })

  output$info <- renderText({
    paste0("x=", input$plot_click$x, "\ny=", input$plot_click$y)
  })
  output$temp <- renderTable({ 
    temp <- data.frame(input$plot_click$x,input$plot_click$y)
    return(temp)
  })
}
shinyApp(ui, server)

But 'temp' is never returned to the R environment. What am I doing wrong? How can I do this?

sessionInfo()
R version 3.6.1 (2019-07-05)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 19.10

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.8.0
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.8.0

locale:
 [1] LC_CTYPE=en_IL.UTF-8       LC_NUMERIC=C               LC_TIME=en_IL.UTF-8        LC_COLLATE=en_IL.UTF-8     LC_MONETARY=en_IL.UTF-8    LC_MESSAGES=en_IL.UTF-8   
 [7] LC_PAPER=en_IL.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_IL.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] shiny_1.4.0.2

loaded via a namespace (and not attached):
 [1] compiler_3.6.1  fastmap_1.0.1   magrittr_1.5    R6_2.4.1        promises_1.1.0  later_1.0.0     htmltools_0.4.0 tools_3.6.1     Rcpp_1.0.3      jsonlite_1.6.1  digest_0.6.25  
[12] xtable_1.8-4    httpuv_1.5.2    mime_0.9        rlang_0.4.5

This might be an issue with your version of Shiny. It looks like it works as expected for me. Can you provide a screenshot and your session info? — Eli Miller
– Eli Miller, Commented Apr 18, 2020 at 20:29
@EliMiller Updated with session info. All that is returned to the R environment is 'ui' and 'server'. — user3012926
– user3012926, Commented Apr 18, 2020 at 20:37
I'm not seeing any major differences here. Can you be a little more clear about what you are expecting? Are you trying to get the data.frame from temp out of the render Table function and use it somewhere else as oppose to just displaying the information? — Eli Miller
– Eli Miller, Commented Apr 18, 2020 at 20:53
@EliMiller Yes, I'd like to use it as an ordinary dataframe in R. — user3012926
– user3012926, Commented Apr 18, 2020 at 20:56

Eli Miller · Accepted Answer · 2020-04-18 21:04:12Z

1

Give the following a try. You should be able to use the rv$df variable in replace of temp. The issue is temp is reactive to the user so it needs to be put into a reactive context.

server <- function(input, output) {

  rv <- reactiveValues(
    df = data.frame(x=NA,y=NA)
  )

  observeEvent(input$plot_click, {
    rv$df$x <- input$plot_click$x
    rv$df$y <- input$plot_click$y
  })

  output$plot1 <- renderPlot({
    plot(mtcars$wt, mtcars$mpg)
  })

  output$info <- renderText({
    paste0("x=", input$plot_click$x, "\ny=", input$plot_click$y)
  })
  output$temp <- renderTable({ 
    rv$df
  })
}

answered Apr 18, 2020 at 21:04

Eli Miller

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1 Comment

user3012926 Over a year ago

I still, for some reason, cannot get rv$df to return to the R environment.

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