In my shiny app, I have a render that I want to only execute after a radio button changes values, but only the first time this happens. Is there a way to make it reactive to the first change in value, but not subsequent ones?
Below you will find that observeEvent has arguments such as ignoreInit and once, I would advise that you go and have a look at the function definitions on the official website Event handler. I have also added the shinyjs library with its disable function which I think is handy here.
rm(list=ls())
library(shiny)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
radioButtons("nums", "Will Execute only Once",c("1000" = 1000,"10000" = 10000), selected = 0),
plotOutput("Plot")
)
server <- function(input, output) {
v <- reactiveValues()
observeEvent(input$nums, {
v$data <- rnorm(input$nums)
},ignoreInit = TRUE, once = TRUE)
output$Plot <- renderPlot({
if(is.null(v$data)){
return()
}
disable('nums')
hist(v$data)
box()
})
}
shinyApp(ui, server)
Related
I have a reactive value (some chosen piece of text) and two pieces of reactive code that need to run sequentially: the first shows the text to the user via renderUI(), and the second calls some javascript functions to make modification to the displayed HTML.
I tried having a separate trigger event for the second reactive code, and to have the first reactive code trigger it, as suggested in this answer:
https://community.rstudio.com/t/how-can-i-set-up-triggers-or-execution-order-for-eventreactive-or-observeevent/7720
Like this:
rv <- reactiveValues()
rv$run2 <- 0
observeEvent(whateverTrigger, {
whateverCode
rv$run2 <- rv$run2 + 1
})
observeEvent(rv$run2, {
whateverCode
})
But it seems that this causes the first reactive to be evaluated again and again because it also depends on the rv$run2 reactive.
EDIT
Here is a minimal reprex for the one renderUI and one observeEvent both reacting to the same value. What I want is for the observeEvent to run after the renderUI has finished. What happens though is that it is executed beforehand.
library(shiny)
library(shinyjs)
jsCode <- 'shinyjs.alertnum = function(data) {
alert(data);
}'
ui <- fluidPage(useShinyjs(),
extendShinyjs(text = jsCode, functions = c("alertnum")),
numericInput("num", "Number", 0),
uiOutput("text"))
server <- function(input, output){
output$text<- renderUI({
wellPanel(input$num)
})
observeEvent(input$num, {
js$alertnum(input$num)
})
}
shinyApp(ui, server, options = list("host" = "0.0.0.0", "port" = 7000))
If I use the suggestion quoted and change the observeEvent to react to a different trigger, triggered by the renderUI, this doesn't work as the renderUI is evaluated again and again:
library(shiny)
library(shinyjs)
jsCode <- 'shinyjs.alertnum = function(data) {
alert(data);
}'
ui <- fluidPage(useShinyjs(),
extendShinyjs(text = jsCode, functions = c("alertnum")),
numericInput("num", "Number", 0),
uiOutput("text"))
server <- function(input, output){
trigger <- reactiveVal(0)
output$text<- renderUI({
trigger(trigger() + 1)
print("TEST")
wellPanel(input$num)
})
observeEvent(trigger, {
js$alertnum(input$num)
})
}
shinyApp(ui, server, options = list("host" = "0.0.0.0", "port" = 7000))
Any suggestions?
Thanks!
I am trying to create a table using Shiny, where the user can click on a row in order to see further information about that row. I thought I understood how to do this (see code attached).
However, right now as soon as the user clicks the "getQueue" action button, the observeEvent(input$fileList_cell_clicked, {}) seems to get called. Why would this be called before the user even has the chance to click on a row? Is it also called when the table is generated? Is there any way around this?
I need to replace "output$devel <- renderText("cell_clicked_called")" with code that will have all sorts of errors if there isn't an actual cell to refer to.
Thank you for any advice!
ui <- fluidPage(
actionButton("getQueue", "Get list of queued files"),
verbatimTextOutput("devel"),
DT::dataTableOutput("fileList")
)
shinyServer <- function(input, output) {
observeEvent(input$getQueue, {
#get list of excel files
toTable <<- data.frame("queueFiles" = list.files("queue/", pattern = "*.xlsx")) #need to catch if there are no files in queue
output$fileList <- DT::renderDataTable({
toTable
}, selection = 'single') #, selection = list(mode = 'single', selected = as.character(1))
})
observeEvent(input$fileList_cell_clicked, {
output$devel <- renderText("cell_clicked_called")
})}
shinyApp(ui = ui, server = shinyServer)
minimal error code
DT initializes input$tableId_cell_clicked as an empty list, which causes observeEvent to trigger since observeEvent only ignores NULL values by default. You can stop the reactive expression when this list is empty by inserting something like req(length(input$tableId_cell_clicked) > 0).
Here's a slightly modified version of your example that demonstrates this.
library(shiny)
ui <- fluidPage(
actionButton("getQueue", "Get list of queued files"),
verbatimTextOutput("devel"),
DT::dataTableOutput("fileList")
)
shinyServer <- function(input, output) {
tbl <- eventReactive(input$getQueue, {
mtcars
})
output$fileList <- DT::renderDataTable({
tbl()
}, selection = 'single')
output$devel <- renderPrint({
req(length(input$fileList_cell_clicked) > 0)
input$fileList_cell_clicked
})
}
shinyApp(ui = ui, server = shinyServer)
I am using Plotly's event_data("plotly_click") to do stuff (opening a modal) after the user clicked on a marker in a scatter plot. Afterwards (e.g. closing the modal), event_data("plotly_click") does of course not change and clicking on the same marker therefore does not trigger the same action again.
Minimal example:
library(plotly)
ui <- fluidPage(
plotlyOutput("plot")
)
server <- function(input, output, session) {
output$plot <- renderPlotly({
mtcars %>% plot_ly(x=~disp, y=~cyl)
})
# Do stuff after clicking on a marker in the plot
observeEvent(event_data("plotly_click"), {
print("do some stuff now") # this is not executed after second click on same marker
})
}
shinyApp(ui, server)
I have tried workarounds with shinyjs's onclick, to no avail (it works well in empty areas of the plot but not when clicking on markers):
shinyjs::onclick(id="plot", print("clicked"))
I have also tried using a reactive Value that stores the last click and is reset immediately afterwards (e.g. by event_data("plotly_hover")), but all tries fail because event_data("plotly_click") remains in its old value.
Can anyone help?
[Edit: The issue has been fixed in Plotly 4.9.0. See answer below. This answer works up to Plotly 4.8.0. From plotly 4.9.0., delete the string .clientValue- from the source code or use below answer.]
I finally solved this issue. I know this is bothering some people, so I'll post my solution here:
Basically I use shinyjs package to reset the data about the last click (the source where event_data("plotly_click") gets its information from) on a certain event (a button in my case).
The definition of the function is (note that "A" needs to be replaced with plotly-source string if used):
extendShinyjs(text = "shinyjs.resetClick = function() { Shiny.onInputChange('.clientValue-plotly_click-A', 'null'); }")
Then this is called upon button click by js$resetClick().
Minimal example:
library(shiny)
library(plotly)
library(shinyjs)
ui <- shinyUI(
fluidPage(
useShinyjs(),
# code to reset plotlys event_data("plotly_click", source="A") to NULL -> executed upon action button click
# note that "A" needs to be replaced with plotly source string if used
extendShinyjs(text = "shinyjs.resetClick = function() { Shiny.onInputChange('.clientValue-plotly_click-A', 'null'); }"),
actionButton("reset", "Reset plotly click value"),
plotlyOutput("plot"),
verbatimTextOutput("clickevent")
)
)
server <- shinyServer(function(input, output) {
output$plot <- renderPlotly({
plot_ly(mtcars, x=~cyl, y=~mpg)
})
output$clickevent <- renderPrint({
event_data("plotly_click")
})
observeEvent(input$reset, {
js$resetClick()
})
})
shinyApp(ui, server)
The issue has finally been fixed on Plotly side: https://github.com/ropensci/plotly/issues/1043
event_data("plotly_click", priority = "event") updates on every click, not only on shiny input change (as before). Working from Plotly 4.9.0 on.
Minimal example using Plotly 4.9.0:
library(shiny)
library(plotly)
ui <- shinyUI(
fluidPage(
plotlyOutput("plot", height = 200),
verbatimTextOutput("time_last_click")
)
)
server <- shinyServer(function(input, output) {
output$plot <- renderPlotly({
plot_ly(mtcars[1,], x=~cyl, y=~mpg, size = 1)
})
output$time_last_click <- renderPrint({
tmp <- event_data("plotly_click", priority = "event")
Sys.time()
})
})
shinyApp(ui, server)
I had the same problem, and came up with a solution where I specified the source argument of the plotly object to be a reactive value as follows:
In plot_ly(data,x,y,...,source = x) and event_data(...,source = x) let x be an element of a reactiveValues object. When your event triggers, change the value of x (increment or hash), which instantiates a new event_data() object.
Worked like a charm.
In my Shiny App, there are a few numericInput and selectInput.
Shiny updates outputs during typing, especially when users type is slower in the numericInput.
sumbitButton could you be used to stop automatically updading. But I prefer to not to use it.
How could I let Shiny waits for a longer time for numericInput?
Thanks for any suggestion. Let me know if my question is not clear.
You can use debounce on the reactive function that uses your Inputs.
Setting it to 2000 milliseconds felt OK to me.
If you use the input directly in a render function you might need to create the data to use in your render function in a reactive function.
An example is here: https://shiny.rstudio.com/reference/shiny/latest/debounce.html
## Only run examples in interactive R sessions
if (interactive()) {
options(device.ask.default = FALSE)
library(shiny)
library(magrittr)
ui <- fluidPage(
plotOutput("plot", click = clickOpts("hover")),
helpText("Quickly click on the plot above, while watching the result table below:"),
tableOutput("result")
)
server <- function(input, output, session) {
hover <- reactive({
if (is.null(input$hover))
list(x = NA, y = NA)
else
input$hover
})
hover_d <- hover %>% debounce(1000)
hover_t <- hover %>% throttle(1000)
output$plot <- renderPlot({
plot(cars)
})
output$result <- renderTable({
data.frame(
mode = c("raw", "throttle", "debounce"),
x = c(hover()$x, hover_t()$x, hover_d()$x),
y = c(hover()$y, hover_t()$y, hover_d()$y)
)
})
}
shinyApp(ui, server)
}
Quick question on conditionalPanel for shiny/R.
Using a slightly modified code example from RStudio, consider the following simple shiny app:
n <- 200
# Define the UI
ui <- bootstrapPage(
numericInput('n', 'Number of obs', n),
conditionalPanel(condition = "input.n > 20",
plotOutput('plot') ),
HTML("Bottom")
)
# Define the server code
server <- function(input, output) {
output$plot <- renderPlot({
if (input$n > 50) hist(runif(input$n)) else return(NULL)
})
}
# Return a Shiny app object
shinyApp(ui = ui, server = server)
My objective is to hide the graph and move up the HTML text to avoid a gap. Now, you can see that if the entered value is below 20, the graph is hidden and the text "Bottom" is moved up accordingly. However, if the entered value is larger than 20, but smaller than 50, the chart function returns NULL, and while no chart is shown, the text "Bottom" is not moving up.
Question is: is there a way I can set a conditionalPanel such that it appears/is hidden based on whether or not a plot function returns NULL? The reason I'm asking is because the trigger a bit complex (among other things it depends on the selection of input files, and thus needs to change if a different file is loaded), and I'd like to avoid having to code it on the ui.R file.
Any suggestions welcome,
Philipp
Hi you can create a condition for conditionalPanel in the server like this :
n <- 200
library("shiny")
# Define the UI
ui <- bootstrapPage(
numericInput('n', 'Number of obs', n),
conditionalPanel(condition = "output.cond == true", # here use the condition defined in the server
plotOutput('plot') ),
HTML("Bottom")
)
# Define the server code
server <- function(input, output, session) {
output$plot <- renderPlot({
if (input$n > 50) hist(runif(input$n)) else return(NULL)
})
# create a condition you use in the ui
output$cond <- reactive({
input$n > 50
})
outputOptions(output, "cond", suspendWhenHidden = FALSE)
}
# Return a Shiny app object
shinyApp(ui = ui, server = server)
Don't forget to add the session in your server function and the outputOptions call somewhere in that function.