Update app.R

app.R

@@ -9,7 +9,7 @@ library(sf)
 library(rnaturalearth)
 library(rnaturalearthdata)
 library(countrycode)
-library(leaflet)     # <-- New: for OpenStreetMap-based map
+library(leaflet)     # <-- For OpenStreetMap-based map
 
 # =============================
 #            UI
@@ -321,7 +321,7 @@ server <- function(input, output, session) {
       setView(lng = 0, lat = 20, zoom = 2)  # A broad global view
   })
   
-  # Observe changes in the chosen index and update polygons
+  # Observe changes in the chosen index and update polygons + legend
   observeEvent(input$indexChoice, {
     
     plot_data <- cartogram_sf()
@@ -335,8 +335,6 @@ server <- function(input, output, session) {
     )
     
     # Construct a label/popup-like text
-    # (You could use labelOptions, popup, or separate tooltips)
-    # We'll just use label here for quick hover info:
     labels <- sprintf(
       "<strong>Country:</strong> %s<br/>
        <strong>%s Index:</strong> %s",
@@ -346,7 +344,8 @@ server <- function(input, output, session) {
     ) %>% lapply(htmltools::HTML)
     
     leafletProxy("cartogramPlot", data = plot_data) %>%
-      clearShapes() %>%
+      clearShapes() %>%    # clear existing polygons
+      clearControls() %>%  # clear existing legends
       addPolygons(
         fillColor = ~pal(get(index_col)),
         fillOpacity = 0.7,
@@ -359,6 +358,14 @@ server <- function(input, output, session) {
           weight = 2,
           bringToFront = TRUE
         )
+      ) %>%
+      addLegend(
+        position = "bottomright",
+        pal = pal,
+        bins = 5, 
+        values = plot_data[[index_col]],
+        title = paste(index_col, "Index"),
+        opacity = 1
       )
   }, ignoreNULL = FALSE)  # Trigger once on startup too