Shiny app basic example

app.R

library(shiny)
library(tidyverse)
library(gapminder)

# User Interface
ui <- basicPage(
  
  sliderInput("year", "Select year:", animate = TRUE,
              min = 1952, max = 2007, value = 2007,
              step = 5,
              sep=''   # so thousands are not separated with a comma (without this defaults to 1,952 - 2,007)
              ),       #note this comma here - different to our usual R code
  plotOutput(outputId = "myplot")
  
)

# Server
server <- function(input, output) {
  
  output$myplot <- renderPlot({
    
    gapminder %>% 
      filter(year == input$year) %>% 
      ggplot(aes(y = lifeExp, x = continent)) +
      geom_jitter(aes(size = pop/1000000, fill = lifeExp),
                  shape = 21, colour = "grey", alpha = 0.8, width = 0.15) +
      scale_fill_distiller(palette = "Paired") +
      coord_cartesian(ylim = c(30,85)) +
      scale_size("Population, millions", range = c(5, 25), breaks = c(10, 50, 100, 250, 1000)) +
      theme_bw() +
      labs(caption = "Each bubble is a country.")
    
  })  
  
}

shinyApp(ui, server)