shiny renderUI error - r

I wrote a small Shiny application using renderUI. It ran correctly but the R console thrown out an error message
Error in if (nchar(locus) == 12) { : argument is of length zero
every time I ran this application.
Here are my scripts.
server.R:
load("rapmsu.rda")
convMSU <- function(locus="Os02g0677300") {
if (nchar(locus)==12) {
return(rapmsu[rapmsu$rap==locus,])
} else {
return(NULL)
}
}
convRap <- function(locus="LOC_Os03g57940") {
if (nchar(locus)==14) {
return(rapmsu[rapmsu$msu==locus,])
} else {
return(NULL)
}
}
convID <- function(query="", text="") {
if (query=="RAPdb Locus") {
return(convMSU(text))
} else if (query=="MSU Locus") {
return(convRap(text))
}
}
query.intext.conv <- c("Os02g0677300", "LOC_Os03g57940")
names(query.intext.conv) <- c("RAPdb Locus", "MSU Locus")
#### Shiny
shinyServer(function(input, output) {
output$inTextconv <- renderUI({
textInput("inTextconv", strong("Put your query here:"),
value=query.intext.conv[input$queryconv])
})
output$mytable10 = renderDataTable({
convID(input$queryconv, input$inTextconv)
}, options = list(aLengthMenu = 1, iDisplayLength = 1,
bFilter = FALSE, bAutoWidth = FALSE)
)
})
ui.R:
shinyUI(fluidPage(
fluidRow(
absolutePanel(
br(),
selectInput("queryconv", h4("* Convert ID of MSU genomic locus
and RAPdb genomic locus"),
choices=c("RAPdb Locus", "MSU Locus")),
uiOutput("inTextconv"),
tabsetPanel(
tabPanel(strong('Result'), dataTableOutput("mytable10"))
),
br(),
right=5, left=10
)
)
))
The variable "rapmsu" is a data frame.
> head(rapmsu)
rap msu
1 Os01g0100100 LOC_Os01g01010
2 Os01g0100200 LOC_Os01g01019
3 Os01g0100300 None
4 Os01g0100400 LOC_Os01g01030
5 Os01g0100466 None
6 Os01g0100500 LOC_Os01g01040

Make sure you include all the test cases in your function. Test for NULL and NA first and then proceed to the nchar evaluation. Here's modified example of one of your functions:
convMSU <- function(locus="Os02g0677300") {
if(is.null(locus) || is.na(locus))
{
return()
}
else if (nchar(locus)==12) {
return(rapmsu[rapmsu$rap==locus,])
}
else {
return()
}
}
As you can see I tested for NULL and NA first and then evaluated the expression. As your error says:argument is of length zero

Related

Disable action button in R facing problem for multiple inputs

Hi i am building an R code as follow to have an shiny app
ui = fluidPage(
shinyjs::useShinyjs(),
shinyjs::inlineCSS(appCSS),
shinyFeedback::useShinyFeedback(),
titlePanel("Predicting concrete strength",""),
numericInput("CEM","Cement (kg)",""),
numericInput("Water","Water (kg)",""),
numericInput("PFA","Flyash (kg)",""),
actionButton("submit", "Get the results", class = "btn-primary"),
textOutput("class"),
textOutput("class_prob")
)
and the server code is
server <- function(input, output, session) {
inputsValues = reactiveValues(inputs = NULL)
## to disable action button until all inputs are given
observe({
if(input$CEM!="" && input$Water!= "" && input$PFA!=""){
shinyjs::enable("submit")
} else {
shinyjs::disable("submit")
}
})
# putting some feedback if inputs are wrongly given
observeEvent(input$submit,{
cem_con<- (as.numeric(input$CEM) > 163 & as.numeric(input$CEM) < 3307)
shinyFeedback::feedbackDanger("CEM", !cem_con , " abc")
wat_con<- (as.numeric(input$Water) > 131 & as.numeric(input$Water) < 1640)
shinyFeedback::feedbackDanger("Water",!wat_con , "abc")
pfa_con<-(as.numeric(input$PFA) > 55 & as.numeric(input$PFA) < 1617)
shinyFeedback::feedbackDanger("PFA", !pfa_con, "abc")
req(cem_con,wat_con)
inputsValues$inputs<-c("CEM"=input$CEM,"Water"=input$Water,"PFA"=input$PFA)
inputsValues$inputs<-as.numeric(inputsValues$inputs)
})
output$class_prob<- renderText(inputsValues$inputs)
output$class <- renderText(sum(inputsValues$inputs))
}
and when I run the app using
shinyApp(ui, server)
its stops and give the following error
Listening on http://126.0.0.1:3739
Warning: Error in enable: could not find function "enable"
[No stack trace available]
To check for missing value, you could use is.na() as shown below.
observe({
if (is.na(input$CEM) | is.na(input$Water) | is.na(input$PFA) ) {
shinyjs::disable("submit")
} else {
shinyjs::enable("submit")
}
})

Capture Single Inputs into Vector Output in Shiny R Code

How can I create Vector Output in R Shiny code.
I read this stackechange question, but instead of using textbox, I am using colourpicker::colourInput
Working R code is in GitHub
How do I capture the checked boxes and store color values into a vector? If user unchecks a box, the color value should be removed.
Please give hint on doing this.
Below is animated screenshot and the function
CherryPickPalette <- function (name, name2=NULL, name3=NULL){
if ((nargs() < 2) || (nargs() > 3)){
stop("Enter 2 or 3 valid palettes. Run ListPalette() for list of palettes.")
}
if (nargs() == 2){
new_pal <- MergePalette(name,name2)
}
else if (nargs() == 3){
new_pal <- MergePalette(name,name2,name3)
}
if (interactive()){
shinyApp(
ui = fluidPage(
titlePanel("Cherry Pick Your Own Palette!"),
sidebarPanel (
colourpicker::colourInput("col","Choose colors","white", palette="limited", allowedCols = new_pal)),
mainPanel(
h5('Your custom colors',style = "font-weight: bold;"),
fluidRow(column(12,verbatimTextOutput("value"))))
),
server = function(input,output,session){
output$value<-renderPrint({
paste(input$col,sep=" ")
}
)
}
)
}
}
> CherryPickPalette("Jutti3","Kulfi","Gidha")

How to remove observeEvent in Shiny?

I have function that show modal with one input to change name that execute function when save button is clicked and I have validation bind to input:
editNameDialog <- function(input, value, name, save) {
showModal(modalDialog(
textInput("modalNewName", paste("Enter", name, ":"), value),
title = paste("Edit", name),
easyClose = TRUE,
footer = div(
modalButton("Cancel"),
actionButton("modalSaveName", "Save", class = "btn-primary")
)
))
validName <- function() {
nchar(input$newName) > 5
}
observeEvent(input$modalNewName, {
if (validName()) {
shinyjs::enable("modalSaveName")
} else {
shinyjs::disable("modalSaveName")
}
});
observeEvent(input$modalSaveName, {
save(input$modalNewName)
removeModal()
}, ignoreInit = TRUE, once = TRUE)
}
I call this function like this (from server.R):
editNameDialog(input, "default value", "enter name", function(value) {
other$name <- value
})
it work but when I execute the function two times the observer input$modalNewName is executed two times for each keypress. How can I remove the event before adding new one?
I've fixed the issue by adding validation in javascript:
function observeModalName() {
var save = $('#modalSaveName');
$('#modalNewName').off('keyup').on('keyup', function() {
var self = $(this);
if (self.val().length < 5) {
save.disable();
self.error({message: 'Name must be at least 5 characters long'});
} else {
save.enable();
self.error('remove');
}
});
}
and executed:
shinyjs::runjs("observeModalName()")

Sift through each row in a dataframe and manually classify it

Can someone recommend an efficient way to sift through each row in a dataframe and manually classify it? For example I might be wanting to separate spam from e-mail, or shortlist job adverts, job applicants, or dating agency profiles (I understand Tinder does this by getting you to swipe left or right).
My dataset is small enough to classify manually. I suppose if it was larger I might only want to manually classify a portion of it in order to train a machine-learning algorithm such as Naive Bayes to finish the task for me.
I'll show you what I've got at the moment, but this isn't a particularly original task, so there must be a less crude way to do this that someone has already thought of! (As a newcomer, I'm impressed by the power of R, but also nonplussed when little tasks like clearing the screen or capturing a keystroke turn out to be non-trivial)
# Let us suppose I am using this built-in dataset to draw up a
# shortlist of where I might wish to go on holiday
df <- data.frame(state.x77);
# pp - define a task-specific pretty print function
pp <- function(row) {
print(row); # Example dataset is simple enough to just print the entire row
}
# cls - clear the screen (this hack works on Windows but I've commented it for now)
cls <- function() {
#system("powershell -ExecutionPolicy Bypass -command (New-Object -ComObject Wscript.Shell).SendKeys([string][char]12)");
}
# It would halve the number of keystrokes needed if I knew a way to read
# a single character
readcharacter <- readline;
sift <- function(df, pp)
{
classification = rep('', nrow(df));
for (nRow in 1:nrow(df))
{
cls();
pp(df[nRow,]);
cat("\nEnter 'a' to discard, 'd' to keep, 'q' to quit\n");
char <- '';
while (char != 'a' && char != 'd' && char != 'q') {
char <- readcharacter();
}
if (char == 'q')
break;
classification[nRow] = char;
}
return(cbind(df,classification=classification));
}
result = sift(df, pp);
cls();
cat("Shortlist:\n");
print(row.names(result[result$classification=='d',]));
So how does the StackOverflow community feel about me using this Shiny app to solve my problem? I wouldn't expect to see Shiny used in this early part of data analysis - normally it only comes into play once we have some results we'd like to explore or present dynamically.
Learning Shiny was fun and useful, but I'd much prefer it if a less complicated answer could be found.
library(shiny);
#
# shortlist - function that allows us to shortlist through the rows in a data frame efficiently
#
shortlist <- function(df, sTitle, sRowName) {
createUI <- function() {
listHeading <- list(
textOutput(outputId = "Progress"),
tags$br(),
fluidRow(
column(width=1, sRowName),
column(width=9, textOutput(outputId = "RowName"))));
listFields <- lapply(names(df), function(sFieldname) {
return(fluidRow(
column(width=1, sFieldname),
column(width=9, textOutput(outputId = sFieldname))));
});
listInputs <- list(
tags$br(),
tags$table(
tags$tr(
tags$td(" "),
tags$td(actionButton(inputId="Up", label="W", disabled=TRUE, width="100%"))),
tags$tr(
tags$td(width="100px", actionButton(inputId="Discard", label="Discard, A", width="100%")),
tags$td(width="100px", actionButton(inputId="Down", label="S", disabled=TRUE, width="100%")),
tags$td(width="100px", actionButton(inputId="Keep", label="Keep, D", width="100%")))),
tags$script("
// JavaScript implemented keyboard shortcuts, including lots of conditions to
// ensure we're finished processing one keystroke before we start the next.
var bReady = false;
$(document).on('shiny:recalculating', function(event) {
bReady = false;
});
$(document).on('shiny:recalculated', function(event) {
setTimeout(function() {bReady = true;}, 500);
});
$(document).on('keypress', function(event) {
if (bReady) {
switch(event.key.toLowerCase()) {
case 'a':
document.getElementById('Discard').click();
bReady = false;
break;
case 'd':
document.getElementById('Keep').click();
bReady = false;
break;
}
}
});
// End of JavaScript
"));
listPanel <- list(
title = sTitle,
tags$br(),
conditionalPanel(
condition = paste("input.Keep + input.Discard <", nrow(df)),
append(append(listHeading, listFields), listInputs)));
listShortlist <- list(
tags$hr(),
tags$h4("Shortlist:"),
dataTableOutput(outputId="Shortlist"));
ui <- do.call(fluidPage, append(listPanel, listShortlist));
return(ui);
}
app <- shinyApp(ui = createUI(), server = function(input, output) {
classification <- rep('', nrow(df));
getRow <- reactive({
return (input$Keep + input$Discard + 1);
});
classifyRow <- function(nRow, char) {
if (nRow <= nrow(df)) {
classification[nRow] <<- char;
}
# In interactive mode, automatically stop the app when we're finished
if ( interactive() && nRow >= nrow(df) ) {
stopApp(classification);
}
}
observeEvent(input$Discard, {classifyRow(getRow() - 1, 'a')});
observeEvent(input$Keep, {classifyRow(getRow() - 1, 'd')});
output$Progress = renderText({paste("Showing record", getRow(), "of", nrow(df))});
output$RowName = renderText({row.names(df)[getRow()]});
lapply(names(df), function(sFieldname) {
output[[sFieldname]] <- renderText({df[getRow(), sFieldname]});
});
output$Shortlist <- renderDataTable(options = list(paging = FALSE, searching = FALSE), {
# Mention the 'keep' input to ensure this code is called when the 'keep' button
# is pressed. That way the shortlist gets updated when an item to be added to it.
dummy <- input$Keep;
# Construct the shortlist
shortlist <- data.frame(row.names(df[classification == 'd',]));
colnames(shortlist) <- sRowName;
return(shortlist);
});
});
if (interactive()) {
classification <- runApp(app);
return(cbind(df, classification = classification));
} else {
return(app);
}
}
#
# And now some example code.
# Shortlist the built in state.x77 data set (let us suppose I am drawing up
# a shortlist of where I might wish to go on holiday)
#
df <- data.frame(state.x77);
result <- shortlist(df = df, "Choose states", "State");
if (interactive()) {
cat("Shortlist:\n");
print(row.names(result[result$classification == 'd',]));
} else {
return (result);
}

Shiny saving URL state subpages and tabs

I would like to have a shiny website that keeps the dynamic choices in the URL as output, so you can copy and share the URL.
I took this code as an example:
https://gist.github.com/amackey/6841cf03e54d021175f0
And modified it to my case, which is a webpage with a navbarPage and multiple tabs per element in the bar.
What I would like is the URL to direct the user to the right element
in the first level tabPanel, and the right tab in the second level
tabPanel.
This is, if the user has navigated to "Delta Foxtrot" and then to
"Hotel", then changed the parameters to
#beverage=Tea;milk=TRUE;sugarLumps=3;customer=mycustomer, I would
like the URL to send the user to "Delta Foxtrot" -> "Hotel", instead
of starting at the first tab of the first panel element.
Ideally I would like a working example, since everything I tried so far hasn't worked.
Any ideas?
# ui.R
library(shiny)
hashProxy <- function(inputoutputID) {
div(id=inputoutputID,class=inputoutputID,tag("div",""));
}
# Define UI for shiny d3 chatter application
shinyUI(navbarPage('URLtests', id="page", collapsable=TRUE, inverse=FALSE,
tabPanel("Alfa Bravo",
tabsetPanel(
tabPanel("Charlie",
tags$p("Nothing to see here. Everything is in the 'Delta Foxtrot' 'Hotel' tab")
)
)
)
,tabPanel("Delta Foxtrot",
tabsetPanel(
tabPanel("Golf",
tags$p("Nothing to see here. Everything is in the 'Delta Foxtrot' 'Hotel' tab")
)
,tabPanel("Hotel",
tags$p("This widget is a demonstration of how to preserve input state across sessions, using the URL hash."),
selectInput("beverage", "Choose a beverage:",
choices = c("Tea", "Coffee", "Cocoa")),
checkboxInput("milk", "Milk"),
sliderInput("sugarLumps", "Sugar Lumps:",
min=0, max=10, value=3),
textInput("customer", "Your Name:"),
includeHTML("URL.js"),
h3(textOutput("order")),
hashProxy("hash")
)
)
)
))
# server.R
library(shiny)
url_fields_to_sync <- c("beverage","milk","sugarLumps","customer");
# Define server logic required to respond to d3 requests
shinyServer(function(input, output, clientData) {
# Generate a plot of the requested variable against mpg and only
# include outliers if requested
output$order <- reactiveText(function() {
paste(input$beverage,
if(input$milk) "with milk" else ", black",
"and",
if (input$sugarLumps == 0) "no" else input$sugarLumps,
"sugar lumps",
"for",
if (input$customer == "") "next customer" else input$customer)
})
firstTime <- TRUE
output$hash <- reactiveText(function() {
newHash = paste(collapse=";",
Map(function(field) {
paste(sep="=",
field,
input[[field]])
},
url_fields_to_sync))
# the VERY FIRST time we pass the input hash up.
return(
if (!firstTime) {
newHash
} else {
if (is.null(input$hash)) {
NULL
} else {
firstTime<<-F;
isolate(input$hash)
}
}
)
})
})
# URL.js
<script type="text/javascript">
(function(){
this.countValue=0;
var changeInputsFromHash = function(newHash) {
// get hash OUTPUT
var hashVal = $(newHash).data().shinyInputBinding.getValue($(newHash))
if (hashVal == "") return
// get values encoded in hash
var keyVals = hashVal.substring(1).split(";").map(function(x){return x.split("=")})
// find input bindings corresponding to them
keyVals.map(function(x) {
var el=$("#"+x[0])
if (el.length > 0 && el.val() != x[1]) {
console.log("Attempting to update input " + x[0] + " with value " + x[1]);
if (el.attr("type") == "checkbox") {
el.prop('checked',x[1]=="TRUE")
el.change()
} else if(el.attr("type") == "radio") {
console.log("I don't know how to update radios")
} else if(el.attr("type") == "slider") {
// This case should be setValue but it's not implemented in shiny
el.slider("value",x[1])
//el.change()
} else {
el.data().shinyInputBinding.setValue(el[0],x[1])
el.change()
}
}
})
}
var HashOutputBinding = new Shiny.OutputBinding();
$.extend(HashOutputBinding, {
find: function(scope) {
return $(scope).find(".hash");
},
renderError: function(el,error) {
console.log("Shiny app failed to calculate new hash");
},
renderValue: function(el,data) {
console.log("Updated hash");
document.location.hash=data;
changeInputsFromHash(el);
}
});
Shiny.outputBindings.register(HashOutputBinding);
var HashInputBinding = new Shiny.InputBinding();
$.extend(HashInputBinding, {
find: function(scope) {
return $(scope).find(".hash");
},
getValue: function(el) {
return document.location.hash;
},
subscribe: function(el, callback) {
window.addEventListener("hashchange",
function(e) {
changeInputsFromHash(el);
callback();
}
, false);
}
});
Shiny.inputBindings.register(HashInputBinding);
})()
</script>
EDITED: I ran the example code in the answer, but couldn't get it to work. See screenshot.
UPDATE
Shiny .14 now available on CRAN supports saving app state in a URL. See this article
This answer is a more in-depth answer than my first that uses the entire sample code provided by OP. I've decided to add it as a new answer in light of the bounty. My original answer used a simplified version of this so that someone else coming to the answer wouldn't have to read through any extraneous code to find what they're looking for. Hopefully, this extended version will clear up any difficulties you're having. Parts I've added to your R code are surrounded with ### ... ###.
server.r
# server.R
library(shiny)
url_fields_to_sync <- c("beverage","milk","sugarLumps","customer");
# Define server logic required to respond to d3 requests
shinyServer(function(input, output, session) { # session is the common name for this variable, not clientData
# Generate a plot of the requested variable against mpg and only
# include outliers if requested
output$order <- reactiveText(function() {
paste(input$beverage,
if(input$milk) "with milk" else ", black",
"and",
if (input$sugarLumps == 0) "no" else input$sugarLumps,
"sugar lumps",
"for",
if (input$customer == "") "next customer" else input$customer)
})
firstTime <- TRUE
output$hash <- reactiveText(function() {
newHash = paste(collapse=";",
Map(function(field) {
paste(sep="=",
field,
input[[field]])
},
url_fields_to_sync))
# the VERY FIRST time we pass the input hash up.
return(
if (!firstTime) {
newHash
} else {
if (is.null(input$hash)) {
NULL
} else {
firstTime<<-F;
isolate(input$hash)
}
}
)
})
###
# whenever your input values change, including the navbar and tabpanels, send
# a message to the client to update the URL with the input variables.
# setURL is defined in url_handler.js
observe({
reactlist <- reactiveValuesToList(input)
reactvals <- grep("^ss-|^shiny-", names(reactlist), value=TRUE, invert=TRUE) # strip shiny related URL parameters
reactstr <- lapply(reactlist[reactvals], as.character) # handle conversion of special data types
session$sendCustomMessage(type='setURL', reactstr)
})
observe({ # this observer executes once, when the page loads
# data is a list when an entry for each variable specified
# in the URL. We'll assume the possibility of the following
# variables, which may or may not be present:
# nav= The navbar tab desired (either Alfa Bravo or Delta Foxtrot)
# tab= The desired tab within the specified nav bar tab, e.g., Golf or Hotel
# beverage= The desired beverage selection
# sugar= The desired number of sugar lumps
#
# If any of these variables aren't specified, they won't be used, and
# the tabs and inputs will remain at their default value.
data <- parseQueryString(session$clientData$url_search)
# the navbar tab and tabpanel variables are two variables
# we have to pass to the client for the update to take place
# if nav is defined, send a message to the client to set the nav tab
if (! is.null(data$page)) {
session$sendCustomMessage(type='setNavbar', data)
}
# if the tab variable is defined, send a message to client to update the tab
if (any(sapply(data[c('alfa_bravo_tabs', 'delta_foxtrot_tabs')], Negate(is.null)))) {
session$sendCustomMessage(type='setTab', data)
}
# the rest of the variables can be set with shiny's update* methods
if (! is.null(data$beverage)) { # if a variable isn't specified, it will be NULL
updateSelectInput(session, 'beverage', selected=data$beverage)
}
if (! is.null(data$sugarLumps)) {
sugar <- as.numeric(data$sugarLumps) # variables come in as character, update to numeric
updateNumericInput(session, 'sugarLumps', value=sugar)
}
})
###
})
ui.r
library(shiny)
hashProxy <- function(inputoutputID) {
div(id=inputoutputID,class=inputoutputID,tag("div",""));
}
# Define UI for shiny d3 chatter application
shinyUI(navbarPage('URLtests', id="page", collapsable=TRUE, inverse=FALSE,
tabPanel("Alfa Bravo",
tabsetPanel(
###
id='alfa_bravo_tabs', # you need to set an ID for your tabpanels
###
tabPanel("Charlie",
tags$p("Nothing to see here. Everything is in the 'Delta Foxtrot' 'Hotel' tab")
)
)
)
,tabPanel("Delta Foxtrot",
tabsetPanel(
###
id='delta_foxtrot_tabs', # you need to set an ID for your tabpanels
###
tabPanel("Golf",
tags$p("Nothing to see here. Everything is in the 'Delta Foxtrot' 'Hotel' tab")
)
,tabPanel("Hotel", id='hotel',
tags$p("This widget is a demonstration of how to preserve input state across sessions, using the URL hash."),
selectInput("beverage", "Choose a beverage:",
choices = c("Tea", "Coffee", "Cocoa")),
checkboxInput("milk", "Milk"),
sliderInput("sugarLumps", "Sugar Lumps:",
min=0, max=10, value=3),
textInput("customer", "Your Name:"),
#includeHTML("URL.js"),
###
includeHTML('url_handler.js'), # include the new script
###
h3(textOutput("order")),
hashProxy("hash")
)
)
)
))
url_handler.js
<script>
Shiny.addCustomMessageHandler('setNavbar',
function(data) {
// create a reference to the desired navbar tab. page is the
// id of the navbarPage. a:contains says look for
// the subelement that contains the contents of data.nav
var nav_ref = '#page a:contains(\"' + data.page + '\")';
$(nav_ref).tab('show');
}
)
Shiny.addCustomMessageHandler('setTab',
function(data) {
// pick the right tabpanel ID based on the value of data.nav
if (data.page == 'Alfa Bravo') {
var tabpanel_id = 'alfa_bravo_tabs';
} else {
var tabpanel_id = 'delta_foxtrot_tabs';
}
// combine this with a reference to the desired tab itself.
var tab_ref = '#' + tabpanel_id + ' a:contains(\"' + data[tabpanel_id] + '\")';
$(tab_ref).tab('show');
}
)
Shiny.addCustomMessageHandler('setURL',
function(data) {
// make each key and value URL safe (replacing spaces, etc.), then join
// them and put them in the URL
var search_terms = [];
for (var key in data) {
search_terms.push(encodeURIComponent(key) + '=' + encodeURIComponent(data[key]));
}
window.history.pushState('object or string', 'Title', '/?' + search_terms.join('&'));
}
);
</script>
To test this, call runApp(port=5678) in the directory with your source files. By default, no parameters are specified in the URL, so this will default to the first navbar item and the first tab within that item. To test it with URL parameters, point your browser to: http://127.0.0.1:5678/?nav=Delta%20Foxtrot&tab=Hotel&beverage=Coffee. This should point you to the second navbar tab and the second tab in that navbar item with coffee as the selected beverage.
Here's an example demonstrating how to update the navbar selection, tabset selection, and widget selection using variables defined in the URL
ui <- navbarPage('TEST', id='page', collapsable=TRUE, inverse=FALSE,
# define a message handler that will receive the variables on the client side
# from the server and update the page accordingly.
tags$head(tags$script("
Shiny.addCustomMessageHandler('updateSelections',
function(data) {
var nav_ref = '#page a:contains(\"' + data.nav + '\")';
var tabpanel_id = data.nav == 'Alpha' ? '#alpha_tabs' : '#beta_tabs';
var tab_ref = tabpanel_id + ' a:contains(\"' + data.tab + '\")';
$(nav_ref).tab('show');
$(tab_ref).tab('show');
}
)
")),
tabPanel('Alpha',
tabsetPanel(id='alpha_tabs',
tabPanel('Tab')
)
),
tabPanel('Beta',
tabsetPanel(id='beta_tabs',
tabPanel('Golf'),
tabPanel('Hotel',
selectInput("beverage", "Choose a beverage:", choices = c("Tea", "Coffee", "Cocoa"))
)
)
)
)
server <- function(input, output, session) {
observe({
data <- parseQueryString(session$clientData$url_search)
session$sendCustomMessage(type='updateSelections', data)
updateSelectInput(session, 'beverage', selected=data$beverage)
})
}
runApp(list(ui=ui, server=server), port=5678, launch.browser=FALSE)
Point your browser to this URL after starting the app: http://127.0.0.1:5678/?nav=Beta&tab=Hotel&beverage=Coffee

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