Carto basemaps now require an API key

[temospena]

the default mapview maps are now showing a "Carto API Key required" in the tiles.

In the CARTO documentation, it says:

add it to your tile URL as a key parameter:
https://basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}.png?key=YOUR_KEY

In Leaflet that looks like:

L.tileLayer('https://{s}.basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}.png?key=YOUR_KEY', {
  attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>, &copy; <a href="https://carto.com/attributions">CARTO</a>',
  subdomains: 'abcd', maxZoom: 20
}).addTo(map);

Suggestion to add an argument of token=... to mapview() to be able to produce the mapview maps with CartoDB.Positron and CartoDB.DarkMatter

(not sure if this also needs to be fixed in leaflet)

[tim-salabim]

I also saw this today. For the first time, i guess it's fairlz new... I'll need to think a bit about how to implement this. options() might be a better route than a new argument?

[tim-salabim]

I assume this will need to be addressed in {leaflet.providers} before also. It would make sense for them to implement some way of passing an API key. Then we can think about how to handle this here...

[temospena]

Yeah, they have an open PR here: leaflet-extras/leaflet-providers#702

[gmatosferreira]

After doing some digging on this I figured that the basemap for mapview defaults to "CartoDB.Positron", "CartoDB.DarkMatter", "OpenStreetMap", "Esri.WorldImagery", "OpenTopoMap".

This can be overriden by mapview::mapviewOptions(), through basemaps parameter, which sets option mapviewPlatform.

Workaround while the API key is not supported / how to use another base map

As a workaround while the API key is not supported (or if you want to stop using Carto basemap), you can change the mapview default basemap by editing the option that overrides the default behavior, using one of the following instructions:

# Option 1 (using mapview::mapviewOptions)
mapviewOptions(basemaps = c("Esri.WorldGrayCanvas","Stadia.AlidadeSmoothDark","OpenStreetMap", "Esri.WorldImagery", "OpenTopoMap"))
# Option 2 (changing R options directly, without calling mapview)
options("mapviewBasemaps" = c("Esri.WorldGrayCanvas","Stadia.AlidadeSmoothDark","OpenStreetMap", "Esri.WorldImagery", "OpenTopoMap"))

These changes can be set permanent at project or user level, by including the last instruction (option 2) at .Rprofile file, using either usethis::edit_r_profile("project") or usethis::edit_r_profile("user").

Should mapview change the default basemaps?

Since mapview is widely used in the R ecosystem, I think that having a basemap which requires an API key as the default map does not make sense anymore. A subject for another issue, which I opened at #521.

Anyway, mapview should support the API Key for Carto.

Support for Carto API key

As @temospena mentioned, there is a PR on leaflet-extras/leaflet-providers#702 to update the leaflet free tile providers repository. However, the leaflet R package (used by mapview to render the web maps) uses https://github.com/rstudio/leaflet.providers repository to get the providers list. This repository is a mirror to the one where the PR has been opened and should be updated as well.

I opened a PR to implement the missing changes at rstudio/leaflet.providers#50

Once it has been accepted and the package released on CRAN, I think that the API key support for mapview will be fixed.