Im trying to reproduce this excellent answer: Turn states on a map into clickable objects in Shiny
I have the following dataset available:
library(rgdal)
library(leaflet)
tmp <- tempdir()
url <- "http://personal.tcu.edu/kylewalker/data/mexico.zip"
file <- basename(url)
download.file(url, file)
unzip(file, exdir = tmp)
mexico <- readOGR(dsn = tmp, layer = "mexico", encoding = "UTF-8")
pal <- colorQuantile("YlGn", NULL, n = 5)
state_popup <- paste0("<strong>Estado: </strong>",
mexico$name,
"<br><strong>PIB per c?pita, miles de pesos, 2008: </strong>",
mexico$gdp08)
On top on this data I build the following Shiny Application:
# load necessary packages
library( leaflet )
library( shiny )
library( shinydashboard )
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 ) %>%
addProviderTiles("CartoDB.Positron") %>%
addPolygons( data = mexico
, fillOpacity = 0
, opacity = 0.2
, color = "#000000"
, weight = 2
, layerId = mexico$states
, group = "click.list"
)
})
output$myMap <- renderLeaflet({
foundational.map()
})
click.list <- shiny::reactiveValues( ids = vector() )
shiny::observeEvent( input$myMap_shape_click, {
click <- input$myMap_shape_click
click.list$ids <- c( click.list$ids, click$id )
lines.of.interest <- mexico[ which( mexico$states %in% click.list$ids ) , ]
if( is.null( click$id ) ){
req( click$id )
} else if( !click$id %in% lines.of.interest@data$id ){
leaflet::leafletProxy( mapId = "myMap" ) %>%
addPolylines( data = lines.of.interest
, layerId = lines.of.interest@data$id
, color = "#6cb5bc"
, weight = 5
, opacity = 1
)
} # end of if else statement
}) # end of shiny::observeEvent({})
shiny::observeEvent( input$clearHighlight, {
output$myMap <- leaflet::renderLeaflet({
click.list$ids <- NULL
foundational.map()
}) # end of re-rendering $myMap
}) # end of clearHighlight action button logic
} # end of server
shiny::shinyApp( ui = ui, server = server)
The basic map works. However, what I want to achieve is that when I click a state border is placed around the state. This should happen with the following code:
click <- input$myMap_shape_click
click.list$ids <- c( click.list$ids, click$id )
lines.of.interest <- mexico[ which( mexico$states %in% click.list$ids ) , ]
if( is.null( click$id ) ){
req( click$id )
} else if( !click$id %in% lines.of.interest@data$id ){
leaflet::leafletProxy( mapId = "myMap" ) %>%
addPolylines( data = lines.of.interest
, layerId = lines.of.interest@data$id
, color = "#6cb5bc"
, weight = 5
, opacity = 1
)
}
But clearly something is off. Any thoughts on what goes wrong?
The issue turns out to be quite simple to solve (once you know where to look). You are referencing twice to mexico$states, while it should be mexico$state, so I removed two letters and now it works. See the code below.
Maybe also good to add how I found this out, so you know how to debug similar issues in the future. In the observeEvent, i added print(click). The output of that is:
$id
NULL
$.nonce
[1] 0.2851101
$group
[1] "click.list"
$lat
[1] 22.26199
$lng
[1] -100.2037
So then we see that there is something wrong with the id of the clicks! From there it is simple to see the error, the polygons had ids mexico$states, instead of mexico$state.
Hope this helps!
library(rgdal)
library(leaflet)
tmp <- tempdir()
url <- "http://personal.tcu.edu/kylewalker/data/mexico.zip"
file <- basename(url)
download.file(url, file)
unzip(file, exdir = tmp)
mexico <- readOGR(dsn = tmp, layer = "mexico", encoding = "UTF-8")
pal <- colorQuantile("YlGn", NULL, n = 5)
state_popup <- paste0("<strong>Estado: </strong>",
mexico$name,
"<br><strong>PIB per c?pita, miles de pesos, 2008: </strong>",
mexico$gdp08)
# load necessary packages
library( leaflet )
library( shiny )
library( shinydashboard )
ui <- fluidPage(
# place the contents inside a box
shinydashboard::box(
width = 12
, title = "Click on the map!"
# separate the box by a column
, column(
width = 2
, shiny::actionButton( inputId = "clearHighlight"
, icon = icon( name = "eraser")
, label = "Clear the Map"
, style = "color: #fff; background-color: #D75453; border-color: #C73232"
)
)
# separate the box by a column
, column(
width = 10
, leaflet::leafletOutput( outputId = "myMap"
, height = 850
)
)
) # end of the box
) # end of fluid page
# create the server
server <- function( input, output, session ){
# create foundational map
foundational.map <- shiny::reactive({
leaflet() %>%
#addTiles( urlTemplate = "https://cartodb-basemaps-{s}.global.ssl.fastly.net/light_all/{z}/{x}/{y}.png") %>%
#setView( lng = -87.567215
# , lat = 41.822582
# , zoom = 11 ) %>%
addProviderTiles("CartoDB.Positron") %>%
addPolygons( data = mexico
, fillOpacity = 0
, opacity = 0.2
, color = "#000000"
, weight = 2
, layerId = mexico$state
, group = "click.list"
)
})
output$myMap <- renderLeaflet({
foundational.map()
})
click.list <- shiny::reactiveValues( ids = vector() )
shiny::observeEvent( input$myMap_shape_click, {
click <- input$myMap_shape_click
click.list$ids <- c( click.list$ids, click$id )
lines.of.interest <- mexico[ which( mexico$state %in% click.list$ids ) , ]
print(click)
if( is.null( click$id ) ){
req( click$id )
} else if( !click$id %in% lines.of.interest@data$id ){
leaflet::leafletProxy( mapId = "myMap" ) %>%
addPolylines( data = lines.of.interest
, layerId = lines.of.interest@data$id
, color = "#6cb5bc"
, weight = 5
, opacity = 1
)
} # end of if else statement
}) # end of shiny::observeEvent({})
shiny::observeEvent( input$clearHighlight, {
output$myMap <- leaflet::renderLeaflet({
click.list$ids <- NULL
foundational.map()
}) # end of re-rendering $myMap
}) # end of clearHighlight action button logic
} # end of server
shiny::shinyApp( ui = ui, server = server)