Hiding Colors in a Map

[omario]

Using the following link as a guide (Possibility of using leaflet.extra::addSearchFeature to addGlPolygons · Issue #18 · r-spatial/leafgl · GitHub), I made this map that I really like in R:

library(sf)  
library(leaflet)
library(leafgl)
library(colourvalues)
library(leaflet.extras)


nc <- st_read(system.file("gpkg/nc.gpkg", package="sf"), quiet = TRUE) %>% 
  st_transform(st_crs(4326)) %>% 
  st_cast('POLYGON')

leaflet(data = nc) %>% addPolygons( stroke = FALSE) %>% addTiles(group = "OSM") %>%  addProviderTiles(provider = providers$OpenStreetMap) %>% addPolygons(data = nc, weight=1, popup = ~NAME,
                label = ~NAME, group = "name", col = 'blue') %>% 
    addSearchFeatures(targetGroups  = 'name', options = searchFeaturesOptions(zoom=10, openPopup=TRUE))

The only thing that I would like to change - I would like to remove the blue color/shading from this map. That is, I would like the user to be able to search for a name on this map (e.g. Edgecombe) - and once the user searchers for this name, ONLY the corresponding region "lights up" in this blue shading.

I tried to do this by manually removing the color option from the leaflet statement:

leaflet(data = nc) %>% addPolygons( stroke = FALSE) %>% addTiles(group = "OSM") %>%  addProviderTiles(provider = providers$OpenStreetMap) %>% addPolygons(data = nc, weight=1, popup = ~NAME,
                label = ~NAME, group = "name" %>% 
    addSearchFeatures(targetGroups  = 'name', options = searchFeaturesOptions(zoom=10, openPopup=TRUE))

But nothing has changed.

• Does anyone have any ideas on how to this? Something like this?

Thank you!

[jlacko]

Removing the blue color is possible; set it's opacity to zero. Such as in here - setting fillOpacity of the polygons to zero.

Unfortunately I am not aware of a way to flip the color back for the single polygon found; I don't think it is possible, at least without writing custom javascript.

library(sf)  
library(leaflet)
library(leafgl)
library(leaflet.extras)


nc <- st_read(system.file("gpkg/nc.gpkg", package="sf"), quiet = TRUE) %>% 
  st_transform(st_crs(4326)) %>% 
  st_cast("POLYGON")

leaflet(data = nc) %>% 
  addProviderTiles(provider = providers$OpenStreetMap) %>% 
  addPolygons(data = nc, 
              weight=1, 
              popup = ~NAME,
              label = ~NAME, 
              group = "name", 
              col = 'blue', 
              fillOpacity = 0) %>% 
  addSearchFeatures(targetGroups  = 'name', 
                    options = searchFeaturesOptions(zoom=10, openPopup=TRUE))

[omario]

Thank you so much for your answer! Can you please explain what you mean by "writing custom Javascript"? Is this possible in R itself? Do you think this would be difficult?

Thank you so much!

[jlacko]

In R you can do a lot, but the interactivity required would need to happen outside of your R session; the leaflet map is a standalone piece of work.

The javascript providing the search feature is distributed as a part of {leaflet.extras} package; the source code is available at leaflet.extras/lfx-search-bindings.js at master · bhaskarvk/leaflet.extras · GitHub .

In theory you should be able to clone it and amend slightly so that the color of a feature found changes.

In practice this would be way over my (very limited) javascript knowledge.

[omario]

thank you for your reply I wish there was some tutorial that would show you how to do this!