Simple Shiny app, with and without plot caching

1-original.R

library(ggplot2)
library(shiny)

ui <- fluidPage(
  varSelectInput("color_by", "Color by:", diamonds, selected = "cut"),
  plotOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlot({
    ggplot(diamonds, aes(carat, price, color = !!input$color_by)) +
      geom_point()
  })
}

shinyApp(ui, server)

2-caching.R

library(ggplot2)
library(shiny)

shinyOptions(cache = diskCache("plot_cache"))

ui <- fluidPage(
  varSelectInput("color_by", "Color by:", diamonds, selected = "cut"),
  plotOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderCachedPlot({
    ggplot(diamonds, aes(carat, price, color = !!input$color_by)) + geom_point()
  }, cacheKeyExpr = { input$color_by })
}

shinyApp(ui, server)