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library(shiny)
library(bslib)
# Define UI for slider demo app ----
ui <- page_sidebar(
# App title ----
title = "More Widgets",
# Sidebar panel for inputs ----
sidebar = sidebar(
# Input: Select a dataset ----
selectInput(
"dataset",
"Choose a dataset:",
choices = c("rock", "pressure", "cars")
),
# Input: Specify the number of observations to view ----
numericInput("obs", "Number of observations to view:", 10),
# Include clarifying text ----
helpText(
"Note: while the data view will show only the specified",
"number of observations, the summary will still be based",
"on the full dataset."
),
# Input: actionButton() to defer the rendering of output ----
# until the user explicitly clicks the button (rather than
# doing it immediately when inputs change). This is useful if
# the computations required to render output are inordinately
# time-consuming.
actionButton("update", "Update View")
),
# Output: Header + summary of distribution ----
h4("Summary"),
verbatimTextOutput("summary"),
# Output: Header + table of distribution ----
h4("Observations"),
tableOutput("view")
)
# Define server logic to summarize and view selected dataset ----
server <- function(input, output) {
# Return the requested dataset ----
# Note that we use eventReactive() here, which depends on
# input$update (the action button), so that the output is only
# updated when the user clicks the button
datasetInput <- eventReactive(
input$update,
{
switch(
input$dataset,
"rock" = rock,
"pressure" = pressure,
"cars" = cars
)
},
ignoreNULL = FALSE
)
# Generate a summary of the dataset ----
output$summary <- renderPrint({
dataset <- datasetInput()
summary(dataset)
})
# Show the first "n" observations ----
# The use of isolate() is necessary because we don't want the table
# to update whenever input$obs changes (only when the user clicks
# the action button)
output$view <- renderTable({
head(datasetInput(), n = isolate(input$obs))
})
}
# Create Shiny app ----
shinyApp(ui, server)
|
