Mass shootings

Building Web Applications with Shiny in R

Ramnath Vaidyanathan

VP of Product Research

Explore data

The first 10 rows from the mass shootings dataset

An app displaying red circles for each mass shooting incident with details appearing on clicking the circle

Add UI

ui <- bootstrapPage(
  theme = shinythemes::shinytheme('simplex'),

  leaflet::leafletOutput('map', width = '100%', height = '100%'),

  absolutePanel(top = 10, right = 10, id = 'controls',

    sliderInput('nb_fatalities', 'Minimum Fatalities', 1, 40, 10),

    dateRangeInput('date_range', 'Select Date', "2010-01-01", "2019-12-01"),

  )

  , tags$style(type = "text/css", "
    html, body {width:100%;height:100%}     
    #controls{background-color:white;padding:20px;}
  ")

)

Add output: interactive map

server <- function(input, output, session){

  output$map <- leaflet::renderLeaflet({

    leaflet() %>%

      addTiles() %>%

      setView( -98.58, 39.82, zoom = 5)

  })

}

An app with an interactive map of the US and controls to select a date range and number of fatalities

Add reactive expression

rval_mass_shootings <- reactive({

  mass_shootings %>%

    filter(

      date >= input$date_range[1],

      date <= input$date_range[2],

      fatalities >= input$nb_fatalities

    )

})

Update output: interactive map

output$map <- leaflet::renderLeaflet({

  rval_mass_shootings() %>%

    leaflet() %>% 
      addTiles() %>%
      setView( -98.58, 39.82, zoom = 5) %>%

      addCircleMarkers(

        popup = ~ summary,

        radius = ~ fatalities,

        fillColor = 'red', color = 'red', weight = 1

      )

})

An app displaying red circles for each mass shooting incident with details appearing on clicking the circle

Update app: add action button and modal

ui <- bootstrapPage(
  theme = shinythemes::shinytheme('simplex'),
  leaflet::leafletOutput('map', width = '100%', height = '100%'),
  absolutePanel(top = 10, right = 10, id = 'controls',
    sliderInput('nb_fatalities', 'Minimum Fatalities', 1, 40, 10),
    dateRangeInput('date_range', 'Select Date', "2010-01-01", "2019-12-01"),

    actionButton('show_about', 'About')

  )
)

server <- function(input, output, session){

  observeEvent(input$show_about, {

    showModal(modalDialog(text_about, title = 'About'))

  })

}

An app displaying red circles for each mass shooting incident with details appearing on clicking the circle

Let's practice!

Building Web Applications with Shiny in R