Related
I am creating a shiny app and realized I am repeating a particular UI element so I am wondering if there is a way to wrap this in a function and supply parameters to make it work in different cases. In my server file, I have
output$loss <- renderUI({
req(input$got)
if(input$got %in% Years) return(numericInput('got_snow', label = 'John Snow', value = NA))
if(!input$got %in% Years) return(fluidRow(column(3)))
})
and in the ui file, I have:
splitLayout(
cellWidths = c("30%","70%"),
selectInput('got', label = 'Select age', choices = c('',Years) , selected = NULL),
uiOutput("loss")
)
Since I find myself using these several times and only changing a few things in both the UI and server files, I wanted to wrap these in a function and use them as and when I please. I tried this for the server file
ui_renderer <- function(in_put, label, id){
renderUI({
req(input[[in_put]])
if(input[[in_put]] %in% Years) return(numericInput(id, label = label, value = NA))
if(!input[[in_put]] %in% Years) return(fluidRow(column(3)))
})
}
output$p_li <- ui_renderer(input='li', "Enter age", id="c_li")
and in my ui file, I put
uiOutput('c_li')
but it's not working. Any help is greatly appreciated.
I was unable to test your code since there was no minimal working example. I don't know if this is a typo in your example, but your are trying to render c_li, but your output is called p_li. Not sure how wrapping a render object in a standard function works, but I have done something similar using reactive values instead.
This is a minimal example using some of your terminology. It is not a working example, but an outline of the idea to my proposed solution.
# Set up the UI ----
ui <- fluidPage(
uiOutput("loss")
)
# Set up the server side ----
server <- function(input, output, session) {
# Let us define reactive values for the function inputs
func <- reactiveValues(
value <- "got",
label <- "select age",
id <- "xyz"
)
# Set up an observer for when any of the reactive values change
observeEvent({
func$value
func$label
func$id
}, {
# Render a new UI any time a reactive value changes
output[["loss"]] <- renderUI(
if (input[[func$value]] %in% years) {
numericInput(func$id, label = func$label, value = NA)
} else {
fluidRow(
column(3)
)
}
)
})
}
# Combine into an app ----
shinyApp(ui = ui, server = server)
The general idea is to define a set of reactive values and set up an observer that will render the UI every time one or more of the reactive values change. You can assign a new value to any of the reactive values using direct assignment, e.g. current$value <- "object_two". Making that change will update the UI using Shiny's reactive pattern, which means you only need to change one value to update the UI.
In a shiny app (by RStudio), on the server side, I have a reactive that returns a list of variables by parsing the content of a textInput. The list of variables is then used in selectInput and/or updateSelectInput.
I can't make it work. Any suggestions?
I have made two attempts. The first approach is to use the reactive outVar directly into selectInput. The second approach is to use the reactive outVar in updateSelectInput. Neither works.
server.R
shinyServer(
function(input, output, session) {
outVar <- reactive({
vars <- all.vars(parse(text=input$inBody))
vars <- as.list(vars)
return(vars)
})
output$inBody <- renderUI({
textInput(inputId = "inBody", label = h4("Enter a function:"), value = "a+b+c")
})
output$inVar <- renderUI({ ## works but the choices are non-reactive
selectInput(inputId = "inVar", label = h4("Select variables:"), choices = list("a","b"))
})
observe({ ## doesn't work
choices <- outVar()
updateSelectInput(session = session, inputId = "inVar", choices = choices)
})
})
ui.R
shinyUI(
basicPage(
uiOutput("inBody"),
uiOutput("inVar")
)
)
A short while ago, I posted the same question at shiny-discuss, but it has generated little interest, so I'm asking again, with apologies, https://groups.google.com/forum/#!topic/shiny-discuss/e0MgmMskfWo
Edit 1
#Ramnath has kindly posted a solution that appears to work, denoted Edit 2 by him. But that solution does not address the problem because the textinput is on the ui side instead of on the server side as it is in my problem. If I move the textinput of Ramnath's second edit to the server side, the problem crops up again, namely: nothing shows and RStudio crashes. I found that wrapping input$text in as.character makes the problem disappear.
Edit 2
In further discussion, Ramnath has shown me that the problem arises when the server attempts to apply the dynamic function outVar before its arguments have been returned by textinput. The solution is to first check whether is.null(input$inBody) exists.
Checking for existence of arguments is a crucial aspect of building a shiny app, so why did I not think of it? Well, I did, but I must have done something wrong! Considering the amount of time I spent on the problem, it's a bitter experience. I show after the code how to check for existence.
Below is Ramnath's code with textinput moved to the server side. It crashes RStudio so don't try it at home. (I have used his notation)
library(shiny)
runApp(list(
ui = bootstrapPage(
uiOutput('textbox'), ## moving Ramnath's textinput to the server side
uiOutput('variables')
),
server = function(input, output){
outVar <- reactive({
vars <- all.vars(parse(text = input$text)) ## existence check needed here to prevent a crash
vars <- as.list(vars)
return(vars)
})
output$textbox = renderUI({
textInput("text", "Enter Formula", "a=b+c")
})
output$variables = renderUI({
selectInput('variables2', 'Variables', outVar())
})
}
))
The way I usually check for existence is like this:
if (is.null(input$text) || is.na(input$text)){
return()
} else {
vars <- all.vars(parse(text = input$text))
return(vars)
}
Ramnath's code is shorter:
if (!is.null(mytext)){
mytext = input$text
vars <- all.vars(parse(text = mytext))
return(vars)
}
Both seem to work, but I'll be doing it Ramnath's way from now on: maybe an unbalanced bracket in my construct had earlier prevented me to make the check work? Ramnath's check is more direct.
Lastly, I'd like to note a couple of things about my various attempts to debug.
In my debugging quest, I discovered that there is an option to "rank" the priority of "outputs" on the server side, which I explored in an attempt to solve my problem, but didn't work since the problem was elsewhere. Still, it's interesting to know and seems not very well known at this time:
outputOptions(output, "textbox", priority = 1)
outputOptions(output, "variables", priority = 2)
In that quest, I also tried try:
try(vars <- all.vars(parse(text = input$text)))
That was pretty close, but still did not fix it.
The first solution I stumbled upon was:
vars <- all.vars(parse(text = as.character(input$text)))
I suppose it would be interesting to know why it worked: is it because it slows things down enough? is it because as.character "waits" for input$text to be non-null?
Whatever the case may be, I am extremely grateful to Ramnath for his effort, patience and guidance.
You need to use renderUI on the server side for dynamic UIs. Here is a minimal example. Note that the second drop-down menu is reactive and adjusts to the dataset you choose in the first one. The code should be self-explanatory if you have dealt with shiny before.
runApp(list(
ui = bootstrapPage(
selectInput('dataset', 'Choose Dataset', c('mtcars', 'iris')),
uiOutput('columns')
),
server = function(input, output){
output$columns = renderUI({
mydata = get(input$dataset)
selectInput('columns2', 'Columns', names(mydata))
})
}
))
EDIT. Another Solution using updateSelectInput
runApp(list(
ui = bootstrapPage(
selectInput('dataset', 'Choose Dataset', c('mtcars', 'iris')),
selectInput('columns', 'Columns', "")
),
server = function(input, output, session){
outVar = reactive({
mydata = get(input$dataset)
names(mydata)
})
observe({
updateSelectInput(session, "columns",
choices = outVar()
)})
}
))
EDIT2: Modified Example using parse. In this app, the text formula entered is used to dynamically populate the dropdown menu below with the list of variables.
library(shiny)
runApp(list(
ui = bootstrapPage(
textInput("text", "Enter Formula", "a=b+c"),
uiOutput('variables')
),
server = function(input, output){
outVar <- reactive({
vars <- all.vars(parse(text = input$text))
vars <- as.list(vars)
return(vars)
})
output$variables = renderUI({
selectInput('variables2', 'Variables', outVar())
})
}
))
As far as I can tell, the problem is that input$inBody does not retrieve a character even though the selectInput function is given a character as value, namely value = "a+b+c". The solution is therefore to wrap input$inBody in a as.character
The following works:
The observe approach with updateSelectInput:
observe({
input$inBody
vars <- all.vars(parse(text=as.character(input$inBody)))
vars <- as.list(vars)
updateSelectInput(session = session, inputId = "inVar", choices = vars)
})
The reactive approach with selectInput:
outVar <- reactive({
vars <- all.vars(parse(text=as.character(input$inBody)))
vars <- as.list(vars)
return(vars)
})
output$inVar2 <- renderUI({
selectInput(inputId = "inVar2", label = h4("Select:"), choices = outVar())
})
Edit: I have edited my question with an explanation based on Ramnath's feedback. Ramnath has explained the problem and provided a better solution, which I give as an edit of my question. I'll keep this answer for the record.
server.R
### This will create the dynamic dropdown list ###
output$carControls <- renderUI({
selectInput("cars", "Choose cars", rownames(mtcars))
})
## End dynamic drop down list ###
## Display selected results ##
txt <- reactive({ input$cars })
output$selectedText <- renderText({ paste("you selected: ", txt() ,sep="") })
## End Display selected results ##
ui.R
uiOutput("carControls"),
br(),
textOutput("selectedText")
Here is the context :
library(shiny)
liste_statut <- c("A","B","C")
ui <- shinyUI(fluidPage(uiOutput("testUI")))
server <- function(input, output, session) {
output$testUI <- renderUI({
navbarPage(
title = "Test",
tabPanel(icon = icon("users"), 'Test',
sidebarPanel(
# Statut
checkboxGroupInput("statut", "Statut", liste_statut, liste_statut),
checkboxInput('selectall_statut', 'Tout / Aucun', T))))
})
# observe({
# updateCheckboxGroupInput(
# session, 'statut', choices = liste_statut,
# selected = if (input$selectall_statut) liste_statut
# )
# })
}
shinyApp(ui = ui, server = server)
I would like to use my checkbox All/None (in comment lines) properly cause in this case i have a "Warning: Error in if: argument is of length zero". Where should i put it or maybe should i redefine properly something in the UI part?
I willingly use the renderUI/uiOutput option (contrary to the "standard mode" ui/server) because in future, i will add an authentification module, so be able to display several "panels" according to user.
Thanks and sorry for my terrible english :).
The following works for me:
library(shiny)
liste_statut <- c("A","B","C")
ui <- shinyUI(fluidPage(uiOutput("testUI")))
server <- function(input, output, session) {
output$testUI <- renderUI({
navbarPage(
title = "Test",
tabPanel(icon = icon("users"), 'Test',
sidebarPanel(
# Statut
checkboxGroupInput("statut", "Statut", liste_statut, liste_statut),
checkboxInput('selectall_statut', 'Tout / Aucun', T))))
})
observeEvent(input$selectall_statut,{
val <- liste_statut
if(!input$selectall_statut)
val <- character(0)
updateCheckboxGroupInput(
session, 'statut',
selected = val
)
})
}
I initially tried selected = ifelse(input$selectall_statut, liste_statut, character(0)) instead of the intermediate variable val. However, ifelse() only returned a single value, not a vector.
If you are going to do this many times over, then I would recommend a custom ifelse function. Perhaps something like the following:
ifelse2 <- function(test, yes, no){
if(test)
return(yes)
return(no)
}
I am trying to dynamically populate the values of the selectInput from the data file uploaded by the user. The selectInput must contain only numeric columns.
Here is my code snippet for server.R
...
idx <- sapply(data.file, is.numeric)
numeric_columns <- data.file[, idx]
factor_columns <- data.file[, !idx]
updateSelectInput(session, "bar_x", "Select1", choices = names(numeric_columns))
updateSelectInput(session, "bar_y", "Select2", choices = names(factor_columns))
...
Corresponding ui.r
...
selectInput("bar_x", "Select1", choices = NULL),
selectInput("bar_y", "Select2", choices = NULL)
...
The code works fine as long as there are more than one values in any dropdown. However, it fails as soon as it encounters only one value to be displayed in the selectInput.
How can I handle this specific condition, given that the data is uploaded and it cannot be controlled if there is just one column as numeric?
It appears that in 2019, this issue still exists. The issue that I have seen is that when there is only one option in the dropdown, the name of the column is displayed instead of the one option.
This appears to only be a graphical problem, as querying the value for the selectInput element returns the correct underlying data.
I was unable to figure out why this problem exists, but an easy way around this bug is to simply change the name of the column so that it looks like the first element in the list.
library(shiny)
ui <- fluidPage(
selectInput("siExample",
label = "Example Choices",
choices = list("Loading...")),
)
server <- function(input, output, session) {
# load some choices into a single column data frame
sampleSet <- data.frame(Example = c("test value"))
# rename the set if there is only one value
if (length(sampleSet$Example) == 1) {
# This should only be done on a copy of your original data,
# you don't want to accidentally mutate your original data set
names(sampleSet) <- c(sampleSet$Example[1])
}
# populate the dropdown with the sampleSet
updateSelectInput(session,
"siExample",
choices = sampleSet)
}
shinyApp(ui = ui, server = server)
Info: Code was adapted by OP to make error reproducible.
To solve your issue use val2 <- val[,idx, drop = FALSE]
You dropped the column names by subsetting the data.frame().
To avoid this use drop = FALSE; see Keep column name when select one column from a data frame/matrix in R.
library(shiny)
# Define UI for application that draws a histogram
ui <- fluidPage(
# Sidebar with a slider input for number of bins
sidebarLayout(
sidebarPanel(
# drj's changes START block 1
#selectInput('states', 'Select states', choices = c(1,2,4))
selectInput('states', 'Select states', choices = NULL)
# drj's changes END block 1
),
# Show a plot of the generated distribution
mainPanel(
plotOutput("distPlot")
)
)
)
# Define server logic required to draw a histogram
server <- function(input, output, session) {
observe({
#drj's changes START block 2
#val <- c(1,2,3)
#names(val) <- c("a","b","c")
#updateSelectInput(session, 'states', 'Select states', choices = names(val[1]))
val <- as.data.frame(cbind(c("_1","_2","_3"), c(4, 4, 6)))
names(val) <- c("a","b")
val$b <- as.numeric(val$b)
idx <- sapply(val, is.numeric)
val2 <- val[,idx, drop = FALSE]
updateSelectInput(session, 'states', 'Select states', choices = names(val2))
#drj's changes END block 2
})
}
# Run the application
shinyApp(ui = ui, server = server)
In a shiny app (by RStudio), on the server side, I have a reactive that returns a list of variables by parsing the content of a textInput. The list of variables is then used in selectInput and/or updateSelectInput.
I can't make it work. Any suggestions?
I have made two attempts. The first approach is to use the reactive outVar directly into selectInput. The second approach is to use the reactive outVar in updateSelectInput. Neither works.
server.R
shinyServer(
function(input, output, session) {
outVar <- reactive({
vars <- all.vars(parse(text=input$inBody))
vars <- as.list(vars)
return(vars)
})
output$inBody <- renderUI({
textInput(inputId = "inBody", label = h4("Enter a function:"), value = "a+b+c")
})
output$inVar <- renderUI({ ## works but the choices are non-reactive
selectInput(inputId = "inVar", label = h4("Select variables:"), choices = list("a","b"))
})
observe({ ## doesn't work
choices <- outVar()
updateSelectInput(session = session, inputId = "inVar", choices = choices)
})
})
ui.R
shinyUI(
basicPage(
uiOutput("inBody"),
uiOutput("inVar")
)
)
A short while ago, I posted the same question at shiny-discuss, but it has generated little interest, so I'm asking again, with apologies, https://groups.google.com/forum/#!topic/shiny-discuss/e0MgmMskfWo
Edit 1
#Ramnath has kindly posted a solution that appears to work, denoted Edit 2 by him. But that solution does not address the problem because the textinput is on the ui side instead of on the server side as it is in my problem. If I move the textinput of Ramnath's second edit to the server side, the problem crops up again, namely: nothing shows and RStudio crashes. I found that wrapping input$text in as.character makes the problem disappear.
Edit 2
In further discussion, Ramnath has shown me that the problem arises when the server attempts to apply the dynamic function outVar before its arguments have been returned by textinput. The solution is to first check whether is.null(input$inBody) exists.
Checking for existence of arguments is a crucial aspect of building a shiny app, so why did I not think of it? Well, I did, but I must have done something wrong! Considering the amount of time I spent on the problem, it's a bitter experience. I show after the code how to check for existence.
Below is Ramnath's code with textinput moved to the server side. It crashes RStudio so don't try it at home. (I have used his notation)
library(shiny)
runApp(list(
ui = bootstrapPage(
uiOutput('textbox'), ## moving Ramnath's textinput to the server side
uiOutput('variables')
),
server = function(input, output){
outVar <- reactive({
vars <- all.vars(parse(text = input$text)) ## existence check needed here to prevent a crash
vars <- as.list(vars)
return(vars)
})
output$textbox = renderUI({
textInput("text", "Enter Formula", "a=b+c")
})
output$variables = renderUI({
selectInput('variables2', 'Variables', outVar())
})
}
))
The way I usually check for existence is like this:
if (is.null(input$text) || is.na(input$text)){
return()
} else {
vars <- all.vars(parse(text = input$text))
return(vars)
}
Ramnath's code is shorter:
if (!is.null(mytext)){
mytext = input$text
vars <- all.vars(parse(text = mytext))
return(vars)
}
Both seem to work, but I'll be doing it Ramnath's way from now on: maybe an unbalanced bracket in my construct had earlier prevented me to make the check work? Ramnath's check is more direct.
Lastly, I'd like to note a couple of things about my various attempts to debug.
In my debugging quest, I discovered that there is an option to "rank" the priority of "outputs" on the server side, which I explored in an attempt to solve my problem, but didn't work since the problem was elsewhere. Still, it's interesting to know and seems not very well known at this time:
outputOptions(output, "textbox", priority = 1)
outputOptions(output, "variables", priority = 2)
In that quest, I also tried try:
try(vars <- all.vars(parse(text = input$text)))
That was pretty close, but still did not fix it.
The first solution I stumbled upon was:
vars <- all.vars(parse(text = as.character(input$text)))
I suppose it would be interesting to know why it worked: is it because it slows things down enough? is it because as.character "waits" for input$text to be non-null?
Whatever the case may be, I am extremely grateful to Ramnath for his effort, patience and guidance.
You need to use renderUI on the server side for dynamic UIs. Here is a minimal example. Note that the second drop-down menu is reactive and adjusts to the dataset you choose in the first one. The code should be self-explanatory if you have dealt with shiny before.
runApp(list(
ui = bootstrapPage(
selectInput('dataset', 'Choose Dataset', c('mtcars', 'iris')),
uiOutput('columns')
),
server = function(input, output){
output$columns = renderUI({
mydata = get(input$dataset)
selectInput('columns2', 'Columns', names(mydata))
})
}
))
EDIT. Another Solution using updateSelectInput
runApp(list(
ui = bootstrapPage(
selectInput('dataset', 'Choose Dataset', c('mtcars', 'iris')),
selectInput('columns', 'Columns', "")
),
server = function(input, output, session){
outVar = reactive({
mydata = get(input$dataset)
names(mydata)
})
observe({
updateSelectInput(session, "columns",
choices = outVar()
)})
}
))
EDIT2: Modified Example using parse. In this app, the text formula entered is used to dynamically populate the dropdown menu below with the list of variables.
library(shiny)
runApp(list(
ui = bootstrapPage(
textInput("text", "Enter Formula", "a=b+c"),
uiOutput('variables')
),
server = function(input, output){
outVar <- reactive({
vars <- all.vars(parse(text = input$text))
vars <- as.list(vars)
return(vars)
})
output$variables = renderUI({
selectInput('variables2', 'Variables', outVar())
})
}
))
As far as I can tell, the problem is that input$inBody does not retrieve a character even though the selectInput function is given a character as value, namely value = "a+b+c". The solution is therefore to wrap input$inBody in a as.character
The following works:
The observe approach with updateSelectInput:
observe({
input$inBody
vars <- all.vars(parse(text=as.character(input$inBody)))
vars <- as.list(vars)
updateSelectInput(session = session, inputId = "inVar", choices = vars)
})
The reactive approach with selectInput:
outVar <- reactive({
vars <- all.vars(parse(text=as.character(input$inBody)))
vars <- as.list(vars)
return(vars)
})
output$inVar2 <- renderUI({
selectInput(inputId = "inVar2", label = h4("Select:"), choices = outVar())
})
Edit: I have edited my question with an explanation based on Ramnath's feedback. Ramnath has explained the problem and provided a better solution, which I give as an edit of my question. I'll keep this answer for the record.
server.R
### This will create the dynamic dropdown list ###
output$carControls <- renderUI({
selectInput("cars", "Choose cars", rownames(mtcars))
})
## End dynamic drop down list ###
## Display selected results ##
txt <- reactive({ input$cars })
output$selectedText <- renderText({ paste("you selected: ", txt() ,sep="") })
## End Display selected results ##
ui.R
uiOutput("carControls"),
br(),
textOutput("selectedText")