Helper function that takes a data set id and parameters to query and parse data from the ONS Open Geography API. Technically uses a POST request rather than a GET request.
Usage
get_ons_api_data(
data_id,
query_params = list(where = "1=1", outFields = "*", outSR = "4326", f = "json"),
batch_size = 200,
verbose = TRUE
)Arguments
- data_id
the id of the data set to query, can be found from the Open Geography Portal
- query_params
query parameters to pass into the API, see the ESRI documentation for more information on query parameters - ESRI Query (Feature Service/Layer)
- batch_size
the number of rows per query. This is 250 by default, if you hit errors then try lowering this. The API has a limit of 1000 to 2000 rows per query, and in truth, the actual limit for our method is lower as every ObjectId queried is pasted into the query URL so for every row included in the batch, and especial if those Id's go into the 1,000s or 10,000s they will increase the size of the URL and risk hitting the limit.
- verbose
TRUE or FALSE boolean. TRUE by default. FALSE will turn off the messages to the console that update on what the function is doing
Details
It does a pre-query to understand the ObjectIds for the query you want, and then does a query to retrieve those Ids directly in batches before then stacking the whole thing back together to work around the row limits for a single query.
On the Open Geography Portal, find the data set you're interested in and then use the query explorer to find the information for the query.
This function has been mostly developed for ease of use for dfeR maintainers if you're interested in getting data from the Open Geography Portal more widely you should also look at the boundr package.
Examples
if (interactive()) {
# Specify some parameters
get_ons_api_data(
data_id = "LAD23_RGN23_EN_LU",
query_params =
list(outFields = "column1, column2", outSR = "4326", f = "json")
)
# Just fetch everything
get_ons_api_data(data_id = "LAD23_RGN23_EN_LU")
}