'argument is of length zero' error even when checking for NULL

[tcash21]

I keep getting an 'argument is of length zero' error on startup and when selecting different positions (basically whenever selectInput choices need to update). 

http://ec2-54-227-149-222.compute-1.amazonaws.com:3838/fantasy/

I've included only the relevant code here (playerdf and adf are pre-loaded data.frames). I'm not sure how else to check for the inputs being null other than 

  if(is.null(input$player1) | is.null(input$player2)){

                return(invisible())

        }

I still get the error though even when checking for the nulls. The error is occurring in output$text below:

ui.R:

htmlOutput("text")

server.R:

shinyServer(function(input, output){

        input1Choices <- reactive({

                if(!("All" %in% input$position)) {

                        a <- playerdf[playerdf$pos %in% input$position,]$name

                        return(a)

                } else{

                        return(playerdf$name)

                }

        })

input2Choices <- reactive({

              if(!("All" %in% input$position)) {

                p <- playerdf[-grep(input$player1, playerdf$name),]

                p <- p[p$pos %in% input$position,]

                return(p$name)

                } else {

                        return (playerdf[-grep(input$player1, playerdf$name),]$name)

                }

        })

output$player1 <- renderUI({

                selectInput("player1", "", choices=input1Choices())

        })

output$player2 <- renderUI({

                if(is.null(input$player1))

                        return()

                selectInput("player2", "OR", choices=input2Choices())

        })

output$text <- renderPrint({

        if(is.null(input$player1) | is.null(input$player2)){

                return(invisible())

        }

        x1 <- adf[which(adf$pick1 == input$player1 & adf$pick2 == input$player2),]$betterpick

        x2 <- adf[which(adf$pick1 == input$player2 & adf$pick2 == input$player1),]$betterpick

        tp1 <- playerdf[which(playerdf$name == input$player1),]$timesPicked

        tp2 <- playerdf[which(playerdf$name == input$player2),]$timesPicked

        if(tp1 >= tp2){

                tpmin <- tp2

                tpmax <- tp1

        } else if (tp2 >= tp1){

                tpmin <- tp1

                tpmax <- tp2

        }

if(x1 >= x2){

                y <- paste(input$player1, " was drafted <br>", signif((x1 / tpmin) * 100, 3), "% of the time before ", input$player2, sep="")

                o <- HTML(paste("<p><strong>", y, "</p>", sep=""))

                cat(as.character(o))

        } else {

                y <- paste(input$player1, " was drafted <br>", signif((x1 / tpmax) * 100, 3), "% of the time before ", input$player2, sep="")

                o <- HTML(paste("<p><strong>", y, "</p>"))

                cat(as.character(o))

        }

        })

})

[Zhuo Jia Dai]

There's both output$player1 and input$player1 in your code. Better include your ui.R so we can see

[Zhuo Jia Dai]

https://groups.google.com/d/topic/shiny-discuss/wVvOfIjYygU/discussion

Check that post. Might be relevant.

On Thursday, August 22, 2013 2:53:22 AM UTC+8, tcash21 wrote:

[Winston Chang]

On Wed, Aug 21, 2013 at 11:23 PM, Zhuo Jia Dai <zhuoj...@gmail.com> wrote:

There's both output$player1 and input$player1 in your code. 

That shouldn't cause any problems (although it could be confusing).

-Winston 

[tcash21]

My problem is a bit different in that it does not freeze up the Shiny interface at all, I just see a quick error pop up where the output$text is on the sidePanel saying ''argument is of length zero' but as soon as the reactive input updates, it disappears.

[DZJ]

Do u need to check for if input$position is null?

[tcash21]

Oddly enough, adding a check for is.null(output$player1) seemed to work. However, I see this error in the console:

Error in `$.shinyoutput`(output, player1) : 

  Reading objects from shinyoutput object not allowed.

[tcash21]

Checking for input$position being NULL also worked, so I scrapped the is.null() check on output$player1.