CODEWITHSUNDEEP
rshiny
viktor_r
viktor_r

Reputation: 721

Call Variable from reactive data() in R Shiny App

I would like to call a certain variable within a reactive expression. Something like this:

server.R

library(raster)

shinyServer(function(input, output) {

data <- reactive({
inFile <- input$test #Some uploaded ASCII file
asc <- raster(inFile$datapath) #Reads in the ASCII as raster layer

#Some calculations with 'asc':

asc_new1 <- 1/asc
asc_new2 <- asc * 100
})

output$Plot <- renderPlot({

inFile <- input$test
if (is.null(inFile)
 return (plot(data()$asc_new1)) #here I want to call asc_new1
plot(data()$asc_new2)) #here I want to call asc_new2
})
})

Unfortunately I could't find out how to call asc_new1 and asc_new2 within data(). This one doesn't work:

data()$asc_new1

Upvotes: 6

Views: 8190

Answers (2)

four-eyes
four-eyes

Reputation: 12394

"With data()$asc_new1 you wont be able to access the in the reactive context created variables (at least with the current shiny version). You need data()[1] data()[2] if you put it in a list like MadScone. Calling it with the $ sign would raise

Warning: Unhandled error in observer: $ operator is invalid for atomic vectors

However, the error your getting

Error in data()$fitnew : $ operator not defined for this S4 class

is not only because you access the variable wrong. You named the output of your reactive function data which is reserved name in R. You want to change that to myData or something.

Upvotes: 0

Ciar&#225;n Tobin
Ciar&#225;n Tobin

Reputation: 7526

Reactives are just like other functions in R. You can't do this:

f <- function() {
  x <- 1
  y <- 2
}

f()$x

So what you're within output$Plot() won't work either. You can do what you want by returning a list from data().

data <- reactive({

  inFile <- input$test 
  asc <- raster(inFile$datapath) 
  list(asc_new1 = 1/asc, asc_new2 = asc * 100)

})

Now you can do:

data()$asc_new1

Upvotes: 11

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