R控制台中的错误和警告消息以及闪亮的应用程序中的空白下载图

Question

i am fairly new to shiny. i am trying to build ui that has drop downs (and plots/data display) that are conditional on an initial selection field. i have made a simplified example using the USArrests data set...

https://gist.github.com/gjabel/4059ae889dea4b8ca0ca

or

shiny::runGist('4059ae889dea4b8ca0ca')

i have a couple of things that i can not figure out.

1) i get error messages in the R console relating to the default plot (and subsequent plots).

Warning in min(x) : no non-missing arguments to min; returning Inf

2) i get error messages in the R console relating to the data...

Warning in matrix(align.tmp[(2 - pos):(ncol(x) + 1)], nrow = nrow(x), ncol = ncol(x) +  :
  data length exceeds size of matrix

3) the download plot button returns a blank plot

4) when i select all from the first drop down i get no plot. (i guess this is related to 1)?)

any ideas how to solve any of these (i think they might all be related)?

Answer 1

1 +2) Check the Shiny processing model: http://rstudio.github.io/shiny/tutorial/#execution-scheduling

Simplest solution for your case is to check if df2 is already filled with data:

  getplot <- reactive({
    if(!is.null(input$crime)) {
        df2<-getdf()$df2
        if(dim(df2)[1] != 0){
            ...
        }

and there will be no more errors / warnings.

3) as far as I know you are not allowed to call a reactive function in there! Copy all your code from getplot into content= ... and it should be working.

And add a "contentType = 'image/png'" to take care that a png file will be created.

4) you are trying to plot numerical and factorial data? I expect something like this

plot(df2[,1:4])

will be the solution.

In general: You should get familiar to data frames. Your data perfectly fits into a data frame and not a list. This will fix several conversion problems