shiny R either or filter with two inputs

Question

I created a shiny app and want to implement an "either or" filter.

Let's say everything is preselected, so the table displays completely. If I select one filter, than the other filter is dismissed/ignored/nulled/...

For example I'm selecting 'gears' = 3 and 'carb' is nulled. Than I'm adding 'gears' = 4. After that I'm selecting 'carb' = 1 and the the 'gear' filter is nulled.

Maybe someone can help me with it. I'm wrapping my head around this problem. I think I need to use reactive or eventReactive or some other kind of reactive-expression. But maybe someone here has an idea.

library(shiny)
library(shinyWidgets)

data(mtcars)
allcarbs <- sort(unique(mtcars$carb))
allgears <- sort(unique(mtcars$gear))

ui <- fluidPage(

  pickerInput(inputId = "carbinput",
              label = h4("carb"),
              choices = allcarbs,
              selected = allcarbs,
              multiple = TRUE, options = list('actions-box' = TRUE)),

  h4("or"),

  pickerInput(inputId = "gearinput", 
              label = h4("gears"), 
              choices = allgears, 
              selected = allgears, 
              multiple = TRUE, options = list('actions-box' = TRUE)),

  tableOutput("mtcarstab")
)

server <- function(input, output, session) {

  output$mtcarstab <- renderTable({
    subset(mtcars, 
           gear %in% as.numeric(input$gearinput) |
             carb %in% as.numeric(input$carbinput))
  })
}

shinyApp(ui, server)

Answer 1

a simple solution:

before declaring server or UI, create reactive values

vals=reactiveValues(carb=FALSE,gear=FALSE)

then you can use observeEvent to change them on your server:

observeEvent(input$gearinput,{
vals$gear=TRUE
vals$carb=FALSE
})

observeEvent(input$carbinput,{
vals$gear=FALSE
vals$carb=TRUE
})

mytable=eventReactive(c(vals$gear,vals$carb,input$carb,input$gear),{
if(vals$carb){return(subset(mtcars, 
           carb %in% as.numeric(input$carbinput)))}
else{return(subset(mtcars, 
           gear %in% as.numeric(input$gearinput)))}
})

  output$mtcarstab <- renderTable({
    mytable()
  })

EDIT: I edited the comments into the answer, to make it 100% correct.