Feature request: add a generic function that mimics `mapview::mapview()`

[atsyplenkov]

Hi Kyle 👋

Could you please consider adding a function similar to what mapview::mapview() does? I.e., a generic one that takes an sf/sfc object and plots it depending on the geometry. For example, I foresee it to be something like the following.

I am interested because sometimes I just want to visually inspect the geometry, but I found mapview a bit slow. And mapgl is so responsive!

If you like the approach, I am more than happy to create a PR. It can be scaled for terra support.

library(sf)
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.3.1; sf_use_s2() is TRUE
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
library(mapgl)

mapglview <- function(
    x,
    fill_color = "#1f77b4",
    fill_opacity = 0.7,
    line_color = "#000000",
    line_width = 1,
    circle_radius = 6,
    circle_color = "#1f77b4",
    circle_opacity = 0.7,
    popup = NULL,
    ...) {
  # Get all attribute names if popup is NULL
  if (is.null(popup)) {
    popup <- names(x)[!names(x) %in% attr(x, "sf_column")]
  }

  # Create formatted popup content
  popup_template <- paste(
    sprintf("<strong>%s: </strong>{%s}", popup, popup),
    collapse = "<br>"
  )

  # Create popup for each feature
  x$popup_info <- apply(sf::st_drop_geometry(x[popup]), 1, function(row) {
    glue::glue(popup_template, .envir = as.list(row))
  })

  # Initialize map centered on data
  m <- maplibre(bounds = x, ...)

  # Add source
  m <- add_source(m, "data", x)

  # Determine geometry type
  geom_type <- sf::st_geometry_type(x, by_geometry = FALSE)

  # Add appropriate layers based on geometry type
  if (grepl("POLYGON", geom_type)) {
    m <- m %>%
      add_fill_layer(
        id = "data_fill",
        source = "data",
        fill_color = fill_color,
        fill_opacity = fill_opacity,
        popup = "popup_info"
      ) %>%
      add_line_layer(
        id = "data_line",
        source = "data",
        line_color = line_color,
        line_width = line_width
      )
  } else if (grepl("LINE", geom_type)) {
    m <- m %>%
      add_line_layer(
        id = "data_line",
        source = "data",
        line_color = line_color,
        line_width = line_width,
        popup = "popup_info"
      )
  } else if (grepl("POINT", geom_type)) {
    m <- m %>%
      add_circle_layer(
        id = "data_point",
        source = "data",
        circle_color = circle_color,
        circle_opacity = circle_opacity,
        circle_radius = circle_radius,
        popup = "popup_info"
      )
  }

  # Add navigation control
  m <- add_navigation_control(m)

  return(m)
}

# Set seed for reproducibility
set.seed(1234)

# Define the bounding box for Washington DC (approximately)
bbox <- st_bbox(
  c(
    xmin = -77.119759,
    ymin = 38.791645,
    xmax = -76.909393,
    ymax = 38.995548
  ),
  crs = st_crs(4326)
)

# Generate 30 random points within the bounding box
random_points <- st_as_sf(
  data.frame(
    id = 1:30,
    lon = runif(30, bbox["xmin"], bbox["xmax"]),
    lat = runif(30, bbox["ymin"], bbox["ymax"])
  ),
  coords = c("lon", "lat"),
  crs = 4326
)

# Assign random categories
categories <- c("music", "bar", "theatre", "bicycle")
random_points <- random_points %>%
  mutate(category = sample(categories, n(), replace = TRUE))

polygons <- sf::read_sf(system.file("shape/nc.shp", package = "sf"))

# mapglview(polygons)
# mapglview(random_points)

^{Created on 2024-11-13 with reprex v2.1.0}

[e-kotov]

I was thinking the same in the past few weeks. It's a bit annoying having to type out so much code to have a quick preview of the dataset with popups of all variables upon clicking a feature. For full customization I would of course go for the full syntax of {mapgl} functions, but fore quick previews I still use mapview() with mapviewOptions(platform='leafgl'), as it is just faster to type right now.

[tim-salabim]

FWIW, I am just starting to look into mapgl as a possible platform for mapview, mainly for 2 reasons:

1. maplibre globe view - which I currently cannot find in mapgl, am I correct @walkerke to assume that globe view is not yet available?
2. geoarrow/deck.gl-layers integration. This is ridiculously fast and scales for very very large data (RAM limited really). See https://fosstodon.org/@tim_salabim/113239194257725947 for a peek of rendering 1M+ building footprints rendered onto a leaflet map. For the leaflet integration, we need to go through a lot of hoops, but for maplibre this should be much easier.

I am just starting to get an idea of the API of mapgl, so this may still be a while out, but if someone is keen on helping out, feel free to open a PR in mapview, which I think is the correct place for such a quick preview function, as we already have a lot of helper functions needed for preparing arbitrary data to be put on a web map.

[walkerke]

Excellent @tim-salabim! A couple things:

-- Globe view is supported in mapgl / MapLibre with maplibre() |> set_projection("globe"). This is in the latest CRAN release. As opposed to Mapbox, it doesn't appear that there is a top-level projection parameter so the set_projection() function is required.

-- Others have brought up the idea of supporting deck.gl layers in mapgl (e.g. #37) but I don't know how much development time that would take.

-- There are a couple limitations of mapgl worth considering that I may end up resolving. As opposed to other R mapping packages, mapgl doesn't include color palette functions, and relies on users setting up colors similar to how they'd do it in Mapbox / MapLibre themselves. It also doesn't include automated legend support (which I suppose Leaflet doesn't really do either).

[tim-salabim]

@walkerke here's a first impression of what geoarrow/deck.gl-layers is capable of (rendering 1+M building footprints in Utah):

There's quite a lot left to implement, but this does look promising IMHO :-)

Note, the standard geojson layer takes about 30 secs to load! somehow the gif won't render properly, so you'd have to take my word for it

[kmcd39]

Hm, i was thinking of adding a PR either here or in mapview to support something like this because I've also been craving a quick-map function for maplibre/mapgl.

But the adding to mapview felt less approachable -- just learning the existing code and structure of the package enough to add to it -- felt like a bigger lift than writing a quick function similar to what @atsyplenkov already has above (but with more flexibility to support something like the zcol parameter from mapview and to work as rendering a new map with basetiles vs adding layers). But, i can potentially plug into some of this

[tim-salabim]

Hi @kmcd39
thanks for the comment. I feel similar about the code base of mapview, even though I am the maintainer 🤕 .

My current plan is to finish https://github.com/tim-salabim/geoarrowDeckgl before moving on to implementing anything in mapview (see also the discussion in #71).
However, if you have the time and would like to get started on preparing a PR, I could set up a branch and add the necessary scaffolding for you to start implementing functionality for maplibre/mapbox. In the beginning, a simple function should be enough. We can then iterate to make everything more flexible as needed (most flexible stuff such as addFeatures actually lives in package leafem). I also feel like mapview could benefit from a core rewrite to slim down the code base to a more maintainable level, so this could be a good starting point.

In any case, let me know if you would like to contribute a maplibre/mapbox based mapview method while I still finish up geoarrowDeckgl.

[kmcd39]

Okay!

@tim-salabim I have a generic function in my own repo for now -- mapglview

I used code from @atsyplenkov above to make the tooltips and existing code i had to allow a several options for color interpolation. I think it's pretty smooth and flexible as a starting place!

I implemented the "start a new map or add a layer" very differently from what is currently done in mapview. Instead of adding the + sign as a method to add layers, the function adapts based on the class of the first argument.

Some examples:

[atsyplenkov]

However, if you have the time and would like to get started on preparing a PR, I could set up a branch and add the necessary scaffolding for you to start implementing functionality for maplibre/mapbox. In the beginning, a simple function should be enough.

@tim-salabim @kmcd39 I can help you with that too. If you can create a special branch for it — would be terrific.

[tim-salabim]

@kmcd39 @atsyplenkov I've created an issue and a corresponding branch in the mapview repo for development of mapgl support.

Feel free to fork and start hacking away :-)

And thanks for your support on this!!
Any questions, don't hesitate to ask (probably in the above mentioned issue rather than here)

[tim-salabim]

@kmcd39 just FYI, mapview generally uses the + sign to enable direct supply of data and that was then expanded to mapview objects as well.