arcpullr (version 0.3.2)

get_spatial_layer: Retrieve a feature service layer from an ArcGIS REST API

Description

This function retrieves spatial layers present in Feature Service layers of an ArcGIS REST services API and returns them as an sf object

Usage

get_spatial_layer(
  url,
  out_fields = c("*"),
  where = "1=1",
  token = "",
  sf_type = NULL,
  head = FALSE,
  ...
)

Value

An object of class "sf" of the appropriate layer

Arguments

url

A character string of the url for the layer to pull

out_fields

A character string of the fields to pull for each layer

where

A character string of the where condition. Default is 1=1

token

A character string of the token (if needed)

sf_type

A character string specifying the layer geometry to convert to sf ("esriGeometryPolygon", "esriGeometryPoint", "esriGeometryPolyline"), if NULL (default) the server will take its best guess

head

Logical or numeric. Limits the number of records returned from a query. If TRUE, only the first 5 records will be returned. If numeric, then the number of records specified in head will be returned

...

Additional arguments to pass to the ArcGIS REST POST request (or associated internal functions used to query them)

Details

This is one of the core functions of this package. It retrieves spatial layers from feature services of an ArcGIS REST API designated by the URL. Additional querying features can be passed such as a SQL WHERE statement (where argument) or spatial queries as well as any other types of queries that the ArcGIS REST API accepts (using ...). However, for easier spatial querying see get_layers_by_spatial.

All of the querying parameters are sent via a POST request to the URL, so if there are issues with passing additional parameters via ... first determine how they fit into the POST request and make adjustments as needed. This syntax can be tricky if you're not used to it.

Examples

if (FALSE) {
# lava flows on Reykjanes (pr. 'rake-yah-ness') peninsula in Iceland
lava_flows <- get_spatial_layer(reykjanes_lava_flow_url)
plot_layer(lava_flows, outline_poly = reykjanes_poly)
plot_layer(lava_flows, outline_poly = iceland_poly)
}