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