Add new OpenStreetMap providers

This vignette aims to provide a simple guide on adding a new provider to osmextract. Let’ start loading the package:

library(osmextract)

As of summer 2020, there are several services providing bulk OSM datasets listed here and here. At the moment, we support the following providers:

oe_providers()
#> Check the corresponding help pages to read more details about the fields in each database (e.g. ?geofabrik_zones).
#>   available_providers          database_name number_of_zones number_of_fields
#> 1           geofabrik        geofabrik_zones             476                8
#> 2              bbbike           bbbike_zones             237                5
#> 3    openstreetmap_fr openstreetmap_fr_zones            1187                6

Check the “Comparing the supported OSM providers” for more details on the existing providers.

This package is designed to make it easy to add new providers. There are three main steps to add a new provider: creating the zones, adding the provider and documenting it. They are outlined below.

Adding a provider_zones object to the package

The first and hardest step is to create an sf object analogous to the test_zones object shown below:

names(test_zones)
#> [1] "id"            "name"          "parent"        "level"        
#> [5] "pbf_file_size" "pbf"           "geometry"
str(test_zones[, c(2, 6, 7)])
#> Classes 'sf' and 'data.frame':   2 obs. of  3 variables:
#>  $ name    : chr  "Isle of Wight" "ITS Leeds"
#>  $ pbf     : chr  "https://github.com/ropensci/osmextract/releases/download/0.0.1/geofabrik_isle-of-wight-latest.osm.pbf" "https://github.com/ropensci/osmextract/raw/master/inst/its-example.osm.pbf"
#>  $ geometry:sfc_POLYGON of length 2; first list element: List of 1
#>   ..$ : num [1:7, 1:2] -1.52 -1.66 -1.31 -1.11 -1.03 ...
#>   ..- attr(*, "class")= chr [1:3] "XY" "POLYGON" "sfg"
#>  - attr(*, "sf_column")= chr "geometry"
#>  - attr(*, "agr")= Factor w/ 3 levels "constant","aggregate",..: NA NA
#>   ..- attr(*, "names")= chr [1:2] "name" "pbf"

The output shows the three most important column names:

  1. The zone name (that is used for matching the input place, see oe_match());
  2. The URL endpoint where .pbf files associated with each zone can be downloaded;
  3. The geometry, representing the spatial extent of the dataset.

The object must also include the fields level and id, which are used, respectively, for spatial matching and updating. See oe_match() and oe_update().

The best way to start creating a new _zones object for a new provider is probably by looking at the code we wrote for the first supported provider in data-raw/geofabrik_zones.R. The following commands will clone this repo and open the relevant file:

git clone git@github.com:ropensci/osmextract
rstudio osmextract/osmextract.Rproj

Then in RStudio:

file.edit("data-raw/geofabrik_zones.R")

Create a new script to document the code that generates the new object, e.g. for bbbike:

file.edit("data-raw/bbbike_zones.R")
# or, even better, use
usethis::use_data_raw("bbbike_zones")

After you have created the new provider _zones file, it’s time to add the provider to the package.

Adding the new provider to the package

Once you have created your overview _zones file as outlined in the previous step, you need to modify the following files for the provider to be available for others:

Documenting the provider

The final step is also the most fun: documenting and using the provider. Add an example, mention it in the README and tell others about what this new provider can do! If you want to ask for help on adding a new provider, feel free to open in a new issue in the github repository!

Conclusion

This vignette talks through the main steps needed to extend osmextract by adding new OSM data providers. To see the same information in code form, see the PR that implemented the openstreetmap_fr provider here: https://github.com/ropensci/osmextract/commit/dbf131667a80e5a6837a6c8eb3b967075e1aba16