This question already has an answer here:
- Set global object in Shiny 1 answer
I have a shiny app in which I define an object based on sliders and create a data.frame
from it. This gets used to create a plot, below which I'd like to include a summary table. My issue is that the plot must be defined inside of a reactive object to update based on the sliders, but I found that when I tried to access the object to print a summary inside of a different reactive object, it wasn't found.
I'd like to not run through the same calculation code twice just to get the object into the other reactive object. My two initial ideas:
- I tried using
save(object, file = "...")
inside the first reactive object and then puttingload(file = "...")
inside the second, but it doesn't update. - I thought of defining my object outside of my reactive
plotOutput
definition, but I'm pretty sure it won't update when user inputs are changed; it will just stay with the value of the initialinput
object default settings.
Well, just went ahead and tried the latter idea, and it doesn't even get that far:
- I put it before
shinyServer(...)
and it can't generate the data because my call depends oninput
and it doesn't know aboutinput
at that point. - I put it after
shinyServer(...)
but beforerenderPlot(...)
to try and make sort of a "globally available" object for all output objects, and it scolding me for trying to do something that usesinput
outside of a reactive function.
Here's an example to illustrate, modified from Shiny's "Hello Shiny!" example:
ui.R
library(shiny)
# Define UI for application that plots random distributions
shinyUI(pageWithSidebar(
# Application title
headerPanel("Hello Shiny!"),
# Sidebar with a slider input for number of observations
sidebarPanel(
sliderInput("obs",
"Number of observations:",
min = 1,
max = 1000,
value = 500)
),
# Show a plot of the generated distribution
mainPanel(
plotOutput("distPlot"),
tableOutput("summary")
)
))
server.R
library(shiny)
# Define server logic required to generate and plot a random distribution
shinyServer(function(input, output) {
output$distPlot <- renderPlot({
# generate an rnorm distribution and plot it
dist <- rnorm(input$obs)
hist(dist)
})
output$summary <- renderTable({
#dist <- rnorm(input$obs)
summary <- table(data.frame(cut(dist, 10)))
})
})
If you run it as is, cut
will throw and error because it doesn't know about dist
. If you uncomment the line where we re-define dist
as is done in plotOutput
, then it will work.
This is simple code -- mine is quite a bit more involved and I'd really prefer not to run it twice just to make the same result known to another reactive output.
Suggestions?