This page contains documentation relevant for those wishing to contribute to the package and specific instructions for how to add support for a new geocoding service.
IntroductionThe two core functions to focus on in the package are geo() and reverse_geo(). These functions have very similar layouts, but geo()
is for forward geocoding while reverse_geo()
is for reverse geocoding. The geocode()
and reverse_geocode()
functions only extract input data from a dataframe and pass it to the geo()
and reverse_geo()
functions respectively for geocoding.
Both the geo()
and reverse_geo()
functions take inputs (either addresses or coordinates) and call other functions as needed to deduplicate the inputs, pause to comply with API usage rate policies, and execute queries. Key parameters and settings for geocoding are stored for easy access and display in built-in datasets.
Consider this query:
library(dplyr)
library(tidygeocoder)
df <- tibble(
id = c(1, 2, 1),
locations = c('tokyo', 'madrid', 'tokyo')
)
df %>%
geocode(address = locations, method = 'osm', full_results = TRUE, verbose = TRUE)
#>
#> Number of Unique Addresses: 2
#> Passing 2 addresses to the Nominatim single address geocoder
#>
#> Number of Unique Addresses: 1
#> Querying API URL: https://nominatim.openstreetmap.org/search
#> Passing the following parameters to the API:
#> q : "tokyo"
#> limit : "1"
#> format : "json"
#> HTTP Status Code: 200
#> Query completed in: 1 seconds
#> Total query time (including sleep): 1 seconds
#>
#>
#> Number of Unique Addresses: 1
#> Querying API URL: https://nominatim.openstreetmap.org/search
#> Passing the following parameters to the API:
#> q : "madrid"
#> limit : "1"
#> format : "json"
#> HTTP Status Code: 200
#> Query completed in: 0.5 seconds
#> Total query time (including sleep): 1 seconds
#>
#> Query completed in: 2 seconds
#> # A tibble: 3 × 16
#> id locations lat long place_id licence osm_type osm_id class type
#> <dbl> <chr> <dbl> <dbl> <int> <chr> <chr> <int> <chr> <chr>
#> 1 1 tokyo 35.7 140. 243209120 Data © Ope… relation 1.54e6 boun… admi…
#> 2 2 madrid 40.4 -3.70 272273162 Data © Ope… relation 5.33e6 boun… admi…
#> 3 1 tokyo 35.7 140. 243209120 Data © Ope… relation 1.54e6 boun… admi…
#> # ℹ 6 more variables: place_rank <int>, importance <dbl>, addresstype <chr>,
#> # name <chr>, display_name <chr>, boundingbox <list>
Here is what is going on behind the scenes:
geocode()
function extracts the address data from the input dataframe and passes it to the geo()
function.geo()
function looks for unique inputs and prepares them for geocoding. In this case, there is one duplicate input so we only have two unique inputs.geo()
function must figure out whether to use single address geocoding (1 address per query) or batch geocoding (multiple addresses per query). In this case the specified Nominatim (“osm”) geocoding service does not have a batch geocoding function so single address geocoding is used.geo()
function is called once for each input to geocode all addresses (twice in this case) and the results are combined. If batch geocoding was used then the appropriate batch geocoding function would be called based on the geocoding service specified.min_time_reference
dataset. This behavior can be modified with the min_time
argument.unique_only = TRUE
.geo()
to the geocode()
function. The geocode()
function then combines the returned data with the original dataset.Refer to the notes below on adding a geocoding service for more specific documentation on the code structure.
Adding a New Geocoding ServiceThis section documents how to add support for a new geocoding service to the package. Required changes are organized by file. If anything isn’t clear, feel free to file an issue.
Base all changes on the main branch.
Files to Updateget_api_url()
function accordingly. If arguments need to be added to the get_api_url()
function, make sure to adjust the calls to this function in the geo()
and reverse_geo()
functions accordingly.method
column (which is how the service is specified in the geo()
and geocode()
functions). The generic_name
column has the universal parameter name that is used across geocoding services (ie. “address”, “limit”, etc.) while the api_name
column stores the parameter names that are specific to the geocoding service.generic_name
) unless the parameters are required. Parameters can always be passed to services directly with the custom_query
argument in geo()
or reverse_geo()
.min_time_reference
with the minimum time each query should take (in seconds) according to the geocoding service’s free tier usage restrictions.api_key_reference
if the service requires an API key.batch_limit_reference
.api_info_reference
with links to the service’s website, documentation, and usage policy.batch_func_map
named list.get_coord_parameters()
function based on how the service passed latitude and longitude coordinates for reverse geocoding.reverse_batch_func_map
named list.extract_results()
function which is used for parsing single addresses (ie. not batch geocoding). You can see examples of how I’ve tested out parsing the results of geocoding services here.extract_reverse_results()
function for reverse geocoding.extract_errors_from_results()
function to extract error messages for invalid queries.no_query = TRUE
in the geo()
and geocode()
functions).These files don’t necessarily need to be updated. However, you might need to make changes to these files if the service you are implementing requires some non-standard workarounds.
devtools::check()
to make sure the package still passes all tests and checks, but note that these tests are designed to work offline so they do not make queries to geocoding services.devtools::test()
) because they require API keys which would not exist on all systems and are dependent on the geocoding services being online at that the time of the test.To release a new version of tidygeocoder:
pkgdown::build_site()
(make sure to do this again if you need to make any more updates that show up on the site)urlchecker::url_check()
devtools::spell_check()
Last, run devtools::release()
to release the new version once everything looks good.
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