incRv {spsComps}

In-line numeric operation for reactiveVal

Description

In-place operations like ⁠i += 1⁠, ⁠i -= 1⁠ is not support in R. These functions implement these operations in R. This set of functions will apply this kind of operations on ⁠[shiny::reactiveVal]⁠ objects.

Usage

incRv(react, value = 1)

multRv(react, value = 2)

diviRv(react, value = 2)

Arguments

react

reactiveVal object, when it is called, should return an numeric object

value

the numeric value to do the operation on react

Details

incRv(i) is the same as i <- i + 1. incRv(i, -1) is the same as i <- i - 1. multRv(i) is the same as i <- i * 2. diviRv(i) is the same as i <- i / 2.

Value

No return, will directly change the reactiveVal object provided to the react argument

See Also

If you want shiny::reactiveValues version of these operators or just normal numeric objects, use spsUtil::inc, spsUtil::mult, and spsUtil::divi.

Examples

reactiveConsole(TRUE)
rv <- reactiveVal(0)
incRv(rv) # add 1
rv()
incRv(rv) # add 1
rv()
incRv(rv, -1) # minus 1
rv()
incRv(rv, -1) # minus 1
rv()
rv2 <- reactiveVal(1)
multRv(rv2) # times 2
rv2()
multRv(rv2) # times 2
rv2()
diviRv(rv2) # divide 2
rv2()
diviRv(rv2) # divide 2
rv2()
reactiveConsole(FALSE)
# Real shiny example
if(interactive()){
  ui <- fluidPage(
    textOutput("text"),
    actionButton("b", "increase by 1")
  )
  server <- function(input, output, session) {
    rv <- reactiveVal(0)
    observeEvent(input$b, {
      incRv(rv)
    })
    output$text <- renderText({
      rv()
    })
  }
  shinyApp(ui, server)
}