Leaflet Shiny Intergration slow

[Arjan Hada]

I am trying to build an interactive Choropleth in Shiny using leaflet. However, the load time and recreate time is really slow. Any way to speed it up.

Here is a link to the minimal app folder along with the data: https://www.dropbox.com/home/Leaflet_Shiny_app

global.R

library(shinydashboard)

library(tidyverse)

library(ggvis)

library(leaflet)

library(WDI)

library(sp)

ui.R

header <- dashboardHeader(

  title = "Greenhouse gas (GHG) emissions"

  )

## Sidebar content

sidebar <- dashboardSidebar(

  sidebarMenu(

    menuItem("Interactive Choropleth", tabName = "choropleth")

  )

)  

## Body content

body <- dashboardBody(

    

  # First tab content

  tabItem("choropleth",

          

    fluidRow(

      column(width = 9,

        box(width = NULL, solidHeader = TRUE,

            title = "Greenhouse gas emissions (kt of CO2 equivalent)",

            leafletOutput("choropleth_ghg", height = 500)

        )

      ),

      column(width = 3,

        box(width = NULL, status = "warning",

          selectInput("year", "Year", 

                        choices = seq(1970, 2012, 1), 

                        selected = 2012)

        )

      )

    )

  )

)

dashboardPage(

  header,

  sidebar,

  body

)

server.R

# Read the dataset for choropleth

# From http://data.okfn.org/data/core/geo-countries#data

countries <- geojsonio::geojson_read("json/countries.geojson", what = "sp")

# Download the requested data by using the World Bank's API, 

# parse the resulting JSON file, and format it in long country-year format.

load("who_ghg.RData")

function(input, output, session) {

  

  # Interactive Choropleth map.........................................................

  

  # Reactive expression for the data subsetted to what the user selected

  countries_plus_ghg <- reactive({

    

    # Filter the data to select for the year user selected

    who_ghg_subset <- filter(who_ghg, year == input$year)

    

    # Merge a Spatial object having a data.frame for Choropleth map

    sp::merge(countries, who_ghg_subset, 

              by.x = "ISO_A3", by.y = "iso3c")

  })

  

  # Create the map

  output$choropleth_ghg <- renderLeaflet({

    leaflet(countries) %>% 

      setView(0, 20, zoom = 1) %>%

      addTiles()

  })

  

  # Observer to change the color of countries, labels and legends

  # based on the year user selects in the UI

  observe({

    dat <- countries_plus_ghg()

    

    # Define numeric vector bins to add some color

    bins <- ggplot2:::breaks(c(min(dat$EN.ATM.GHGT.KT.CE, na.rm = TRUE)

                               ,max(dat$EN.ATM.GHGT.KT.CE, na.rm = TRUE)),

                             "width",n = 5)

    

    # Call colorBin to generate a palette function that maps the RColorBrewer 

    #"YlOrRd" colors to our bins.

    pal <- colorBin("YlOrRd", 

                    domain = dat$EN.ATM.GHGT.KT.CE, 

                    bins =  bins)

    

    # Generate the labels with some HTML

    labels <- sprintf(

      "<strong>%s</strong><br/>%g",

      dat$country, dat$EN.ATM.GHGT.KT.CE

    ) %>% lapply(htmltools::HTML)

    

    leafletProxy("choropleth_ghg", data = dat) %>% 

      addPolygons(

        fillColor = ~pal(EN.ATM.GHGT.KT.CE),

        weight = 1,

        opacity = 1,

        color = "white",

        fillOpacity = 0.7,

        highlight = highlightOptions(

          weight = 2,

          color = "#666",

          dashArray = "",

          fillOpacity = 0.7,

          bringToFront = TRUE),

        label = labels,

        labelOptions = labelOptions(

          style = list("font-weight" = "normal", padding = "3px 8px"),

          textsize = "15px",

          direction = "auto")) %>% 

      clearControls() %>% 

      addLegend(pal = pal, values = ~EN.ATM.GHGT.KT.CE, opacity = 0.7, title = NULL,

                position = "bottomleft")

  })

  

}

[Andy Kipp]

This seems like more of a general shiny/leaflet question then specifically related to shinyapps.io. You might try posting this to the shiny-discuss group.

-Andy

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