An Introduction to R Shiny-Live Demo

Meetup description

haddaden Mohamed El Fodil introduces RShiny that makes it easy to build interactive web apps. He then builds an impromptu shiny app for the meetup session.

About Speaker

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He is a Shiny developer and an RStudio certified instructor. He also has a PhD in Economics and an avid R and Shiny developer.

Ihaddaden M. EL Fodil personal website

Ihaddaden M. EL Fodil, Ph.D

Check out his work on GitHub

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An Introduction to Shiny

Shiny allows you to interact with the data by changing the data and analysis. The following code is a demonstration of a shiny app from https://shiny.posit.co/.

Learn how to develop a shiny app from here

library(shiny)
library(bslib)
library(dplyr)
library(ggplot2)
library(ggExtra)

penguins_csv <- "https://raw.githubusercontent.com/jcheng5/simplepenguins.R/main/penguins.csv"

df <- readr::read_csv(penguins_csv)
# Find subset of columns that are suitable for scatter plot
df_num <- df |> select(where(is.numeric), -Year)

ui <- page_sidebar(
  theme = bs_theme(bootswatch = "minty"),
  sidebar = sidebar(
    varSelectInput("xvar", "X variable", df_num, selected = "Bill Length (mm)"),
    varSelectInput("yvar", "Y variable", df_num, selected = "Bill Depth (mm)"),
    checkboxGroupInput(
      "species", "Filter by species",
      choices = unique(df$Species), 
      selected = unique(df$Species)
    ),
    hr(), # Add a horizontal rule
    checkboxInput("by_species", "Show species", TRUE),
    checkboxInput("show_margins", "Show marginal plots", TRUE),
    checkboxInput("smooth", "Add smoother"),
  ),
  plotOutput("scatter")
)

server <- function(input, output, session) {
  subsetted <- reactive({
    req(input$species)
    df |> filter(Species %in% input$species)
  })

  output$scatter <- renderPlot({
    p <- ggplot(subsetted(), aes(!!input$xvar, !!input$yvar)) + list(
      theme(legend.position = "bottom"),
      if (input$by_species) aes(color = Species),
      geom_point(),
      if (input$smooth) geom_smooth()
    )

    if (input$show_margins) {
      margin_type <- if (input$by_species) "density" else "histogram"
      p <- ggExtra::ggMarginal(p, type = margin_type, margins = "both",
        size = 8, groupColour = input$by_species, groupFill = input$by_species)
    }

    p
  }, res = 100)
}

shinyApp(ui, server)

shiny app demonstration from https://shiny.posit.co/