world_map/app.R

In AnneOkk/Feedback_reports_golem: Feedback Reports

# install necessary packages
install.packages( pkgs = c( "devtools", "shiny", "shinydashboard" ) )
# install the development version of leaflet from Github
devtools::install_github( repo = "rstudio/leaflet" )


# load necessary packages
library( leaflet )    
library( shiny )
library( shinydashboard )


# import City of Chicago current community area boundaries
comarea606 <- readRDS( gzcon( url( description = "https://github.com/cenuno/shiny/raw/master/cps_locator/Data/raw-data/comarea606_raw.RDS" ) ) )
# Note: for speed, I loaded the GeoJSON file from the City's
#       data portal and exported the object as an RDS file in another script.
#       To download the raw data yourself, feel free to run this:
#       install.packages( pkgs = c( "sp", "rgdal" ) )
#       comarea606 <- 
#           rgdal::readOGR( dsn = "https://data.cityofchicago.org/api/geospatial/cauq-8yn6?method=export&format=GEOJSON"
#                              , layer = "OGRGeoJSON"
#                              , stringsAsFactors = FALSE
#                             ) 


# create the UI
ui <- fluidPage(
    # place the contents inside a box
    shinydashboard::box(
        width = 12
        , title = "Click on the map!"
        # separate the box by a column
        , column(
            width = 2
            , shiny::actionButton( inputId = "clearHighlight"
                                   , icon = icon( name = "eraser")
                                   , label = "Clear the Map"
                                   , style = "color: #fff; background-color: #D75453; border-color: #C73232"
            )
        )
        # separate the box by a column
        , column(
            width = 10
            , leaflet::leafletOutput( outputId = "myMap"
                                      , height = 850
            )
        )
    ) # end of the box
) # end of fluid page

# create the server
server <- function( input, output, session ){
    
    # create foundational map
    foundational.map <- shiny::reactive({
        leaflet() %>%
            addTiles( urlTemplate = "https://cartodb-basemaps-{s}.global.ssl.fastly.net/light_all/{z}/{x}/{y}.png") %>%
            setView( lng = -87.567215
                     , lat = 41.822582
                     , zoom = 11 ) %>%
            addPolygons( data = comarea606
                         , fillOpacity = 0
                         , opacity = 0.2
                         , color = "#000000"
                         , weight = 2
                         , layerId = comarea606$community
                         , group = "click.list"
            )
    })
    
    output$myMap <- renderLeaflet({
        
        foundational.map()
        
    }) # end of leaflet::renderLeaflet({})
    
    # store the list of clicked polygons in a vector
    click.list <- shiny::reactiveValues( ids = vector() )
    
    # observe where the user clicks on the leaflet map
    # during the Shiny app session
    # Courtesy of two articles:
    # https://stackoverflow.com/questions/45953741/select-and-deselect-polylines-in-shiny-leaflet
    # https://rstudio.github.io/leaflet/shiny.html
    shiny::observeEvent( input$myMap_shape_click, {
        
        # store the click(s) over time
        click <- input$myMap_shape_click
        
        # store the polygon ids which are being clicked
        click.list$ids <- c( click.list$ids, click$id )
        
        # filter the spatial data frame
        # by only including polygons
        # which are stored in the click.list$ids object
        lines.of.interest <- comarea606[ which( comarea606$community %in% click.list$ids ) , ]
        
        # if statement
        if( is.null( click$id ) ){
            # check for required values, if true, then the issue
            # is "silent". See more at: ?req
            req( click$id )
            
        } else if( !click$id %in% lines.of.interest@data$id ){
            
            # call the leaflet proxy
            leaflet::leafletProxy( mapId = "myMap" ) %>%
                # and add the polygon lines
                # using the data stored from the lines.of.interest object
                addPolylines( data = lines.of.interest
                              , layerId = lines.of.interest@data$id
                              , color = "#6cb5bc"
                              , weight = 5
                              , opacity = 1
                ) 
            
        } # end of if else statement
        
    }) # end of shiny::observeEvent({})
    
    
    # Create the logic for the "Clear the map" action button
    # which will clear the map of all user-created highlights
    # and display a clean version of the leaflet map
    shiny::observeEvent( input$clearHighlight, {
        
        # recreate $myMap
        output$myMap <- leaflet::renderLeaflet({
            
            # first
            # set the reactive value of click.list$ids to NULL
            click.list$ids <- NULL
            
            # second
            # recall the foundational.map() object
            foundational.map()
            
        }) # end of re-rendering $myMap
        
    }) # end of clearHighlight action button logic
    
} # end of server

## run shinyApp ##
shiny::shinyApp( ui = ui, server = server)

# end of script #