swap pickerInput on a button press in Shiny - r

Question

I need to update/reverse two inputs from drop down inputs upon a button press. At the moment when I hit the swap button (reverse_xz), it reacts however the updatePickerInput doesn't switch my x and z inputs.
I wanted to have the functionality where, once the swap button is clicked, switch the already selected pickerInputs. Then, all the drop down choices (including the selected) need to get reversed. The reason we have to remove the selected choices from vector is to prevent duplicate selections in both x and z inputs.
I am not sure if I have to render the pickerInput ui on the server side?!
This is my code below:
#global.R
library(shiny)
library(shinydashboard)
library(shinydashboardPlus)
library(shinyWidgets)
library(shinyjs)
#variable labels
my_vars <- c("None"= "NONE",
"All" = "all_all",
"Pro" = "Pro_",
"Locomania" = "locomania_Type",
"Racer" = "race")
#ui.R
ui <- shinydashboardPlus::dashboardPage(
header = shinydashboardPlus::dashboardHeader( ),
body = shinydashboard::dashboardBody( box(textOutput("inputs") ) ),
sidebar = shinydashboardPlus::dashboardSidebar(
shinyWidgets::pickerInput(
inputId = "xvar",
label = "X Axis: ",
choices = my_vars,
options = list(
size = 5),
multiple = FALSE,
selected = "all_all"
),
# Button to reverse the choices
shiny::fluidRow(
shiny::column(12, offset = 4,
shinyWidgets::actionBttn(
inputId = "reverse_xz",
label = "",
style = "simple",
color = "primary",
icon = icon("retweet")
)
)
),
shinyWidgets::pickerInput(
inputId = "zvar",
label = "Z Axis: ",
choices = my_vars,
options = list(
size = 5),
multiple = FALSE,
selected = "race"
)
)
)
#server.R
server <- function(input, output, session) {
#
observe({
if(!is.null(input$reverse_xz))
shinyWidgets::updatePickerInput(session, "zvar",
choices = my_vars[!(my_vars %in% input$xvar)],
selected = isolate(input$zvar) )
shinyWidgets::updatePickerInput(session, "xvar",
choices = my_vars[!(my_vars %in% input$zvar)],
selected = isolate(input$xvar) )
})
# These observers remove the selected choices so both pickers are unique
observe({
if(!is.null(input$zvar))
shinyWidgets::updatePickerInput(session, "xvar",
choices = my_vars[!(my_vars %in% input$zvar)],
selected = isolate(input$xvar) )
})
observe({
if(!is.null(input$xvar))
shinyWidgets::updatePickerInput(session, "zvar",
choices = my_vars[!(my_vars %in% input$xvar)],
selected = isolate(input$zvar) )
})
# output inputs
output$inputs <- renderText({ paste0("x var: ", input$xvar,
"\n\n\n z var:", input$zvar,
"\n\n\nreverse press: ", input$reverse_xz) })
}
shiny::shinyApp(ui= ui, server= server)
Thank you in advance. I have looked at some relavant posts however they couldn't guide me much:
Updatepickerinput with change in pickerinput in Shiny
updatePickerInput not updating values after changing tabs in R shiny
update pickerInput by using updatePickerInput in shiny

Answer 1

Look at this and check if it would be OK for you:
#global.R
library(shiny)
library(shinydashboard)
library(shinydashboardPlus)
library(shinyWidgets)
library(shinyjs)
#variable labels
my_vars <- c("None"= "NONE",
"All" = "all_all",
"Pro" = "Pro_",
"Locomania" = "locomania_Type",
"Racer" = "race")
#ui.R
ui <- shinydashboardPlus::dashboardPage(
header = shinydashboardPlus::dashboardHeader( ),
body = shinydashboard::dashboardBody( box(textOutput("inputs") ) ),
sidebar = shinydashboardPlus::dashboardSidebar(
shinyWidgets::pickerInput(
inputId = "xvar",
label = "X Axis: ",
choices = my_vars,
options = list(
size = 5),
multiple = FALSE,
selected = "all_all"
),
# Button to reverse the choices
shiny::fluidRow(
shiny::column(12, offset = 4,
shinyWidgets::actionBttn(
inputId = "reverse_xz",
label = "",
style = "simple",
color = "primary",
icon = icon("retweet")
)
)
),
shinyWidgets::pickerInput(
inputId = "zvar",
label = "Z Axis: ",
choices = my_vars,
options = list(
size = 5),
multiple = FALSE,
selected = "race"
)
)
)
#server.R
server <- function(input, output, session) {
#
observeEvent(input$reverse_xz, {
shinyWidgets::updatePickerInput(session, "zvar",
choices = my_vars[!(my_vars %in% input$zvar)],
selected = input$xvar)
shinyWidgets::updatePickerInput(session, "xvar",
choices = my_vars[!(my_vars %in% input$xvar)],
selected = input$zvar)
})
observe({
if (input$xvar == input$zvar && (length(input$zvar) > 0 && length(input$xvar) > 0)) {
shinyWidgets::updatePickerInput(session, "zvar",
selected = "")
shinyWidgets::updatePickerInput(session, "xvar",
selected = "")
}
})
# output inputs
output$inputs <- renderText({ paste0("x var: ", input$xvar,
"\n\n\n z var:", input$zvar,
"\n\n\nreverse press: ", input$reverse_xz) })
}
shiny::shinyApp(ui= ui, server= server)
I think that maybe this needs an explanation:
if (input$xvar == input$zvar && (length(input$zvar) > 0 && length(input$xvar) > 0))
So, when user choose two the same inputs, then we are updating pickerInputs, so both will have "Nothing selected" as a sign for user that something goes wrong (or that she/he did something wrong). However, "Nothing selected" is like NULL and we can't use NULL like this NULL == "something" inside if, so I'm checking if some input is NULL using length(input$) > 0, because length of NULL is 0. Instead of length(input$) > 0 you could use !is.null(input$) and maybe you should as it is probably more readable, but I'm leaving this decision for you.