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https://github.com/R-ArcGIS/arcgislayers

ArcGIS Location Services
https://github.com/R-ArcGIS/arcgislayers

Last synced: 3 months ago
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ArcGIS Location Services

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README 

        
---

output: github_document

---



```{r, include = FALSE}

knitr::opts_chunk$set(

  collapse = TRUE,

  comment = "#>",

  fig.path = "man/figures/README-",

  out.width = "100%"

)

```



# arcgislayers 



[![License](https://img.shields.io/badge/License-Apache_2.0-blue.svg)](https://opensource.org/license/apache-2-0)

[![R-CMD-check](https://github.com/R-ArcGIS/arcgislayers/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/R-ArcGIS/arcgislayers/actions/workflows/R-CMD-check.yaml)

[![Lifecycle: stable](https://img.shields.io/badge/lifecycle-stable-brightgreen.svg)](https://lifecycle.r-lib.org/articles/stages.html#stable)

[![](https://cranlogs.r-pkg.org/badges/arcgislayers)](https://cran.r-project.org/package=arcgislayers)



The goal of `{arcgislayers}` is to provide an R interface to the [ArcGIS REST API](https://developers.arcgis.com/rest/).



## Installation



It is recommend you install and use the metapackage `{arcgis}`. You can install the development version of arcgis like so:



``` r

remotes::install_github("r-arcgis/arcgis", dependencies = TRUE)

```



## Usage



### Creating a simple feature object from an ArcGIS FeatureLayer



```{r}

library(arcgis)

```



`arc_open()` takes a URL to create a reference to a remote ArcGIS layer, server, or table. The function can return any of the following classes (corresponding to different ArcGIS service types):



  - `FeatureLayer`

  - `Table`

  - `FeatureServer`

  - `ImageServer`

  - `MapServer`

  - `GroupLayer`

  

For example, you can create a `FeatureLayer` object based on a Feature Server URL:

  

```{r}

furl <- "https://services.arcgis.com/P3ePLMYs2RVChkJx/ArcGIS/rest/services/USA_Counties_Generalized_Boundaries/FeatureServer/0"



county_fl <- arc_open(furl)



county_fl

```



You can then use `arc_select()` to query the feature layer object and return an `sf` object.



If no arguments are provided to `arc_select()` the entire feature layer is returned in memory as an `sf` object. 



```{r}

arc_select(county_fl)

```

### Filtering using `where` or `filter_geom` arguments 



You can also use the `fields` argument to select columns or the `where` argument to subset rows.



For example, using a character vector of column names for `fields` and a simple SQL where clause for  `where` you can select counties with population greater than 1,000,000:



```{r}

arc_select(

  county_fl, 

  fields = c("state_abbr", "population"), 

  where = "population > 1000000"

)

```



For `FeatureLayer` and `Table` objects, and sometimes `ImageServer`s, the `list_fields()` function can be helpful to check available attributes and build a `where` query:



```{r}

list_fields(county_fl)

```



You can also provide a `bbox`, `sfc`, or `sfg` object to the `filter_geom` argument to perform a spatial filter. If the `sfc` object contains more than one geometry, the object is combined with `sf::st_union()`. See documentation for more (`?arc_select`).



```{r}

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



arc_select(

  county_fl,

  filter_geom = sf::st_bbox(nc[1,])

)

```



### Creating a `SpatRaster` from an ArcGIS ImageServer



A `SpatRaster` object from the `{terra}` package can be extracted from an `ImageServer` using `arc_raster()`.



`arc_raster()` will extract the area defined by `xmin`, `ymin`, `xmax`, and `ymax`. You can optionally specify the `width` and `height` of the resultant image. Use `format` to define what type of image is returned.



```{r}

img_url <- "https://landsat2.arcgis.com/arcgis/rest/services/Landsat/MS/ImageServer"



landsat <- arc_open(img_url)



res <- arc_raster(

  landsat, 

  xmin = -71, ymin = 43, 

  xmax = -67, ymax = 47.5, 

  bbox_crs = 4326, 

  width = 500, height = 500

)



terra::plotRGB(res, 4, 3, 2, scale = max(landsat[["maxValues"]]))

```



## Authorization and publication



Authorization is not required for reading any public data sources. 



Workflows that require authorization include:



 - interacting with [non-public](https://doc.arcgis.com/en/arcgis-online/share-maps/share-items.htm) services,

 - publishing a new service (the authorized user must also have [publishing privileges](https://doc.arcgis.com/en/arcgis-online/administer/roles.htm)), and

 - modifying or deleting any existing service (the authorized user must also have [edit access](https://doc.arcgis.com/en/arcgis-online/manage-data/manage-editing-hfl.htm) to the service).



### Accessing non-public data



The same functions for reading public ArcGIS Online and Enterprise services (such as `arc_open()`,`arc_read()`,`arc_select()`,`arc_raster()`, etc.) can be used to read data from non-public services by using the `token` argument.

For more information on tokens and authorization functions, see the [authorization article](https://r.esri.com/r-bridge-site/location-services/connecting-to-a-portal.html).



### Publishing and modifying services from R



The package includes functions to publish data to an ArcGIS Portal:



- `add_item()`: Creates a new FeatureCollection from a `sf` or `data.frame` object

- `publish_item()`: Publishes an existing FeatureLayer

- `publish_layer()`: is a higher level wrapper around both `add_item()` and `publish_item()`



There are also functions to add or modify data including `add_features()`, `update_features()`, and `delete_features()`. For a more detailed guide to adding, updating, and deleting features, view the tutorial on the [R-ArcGIS Bridge website](https://r.esri.com/r-bridge-site/location-services/workflows/add-delete-update.html).



These functions all require authorization since data cannot be published or modified anonymously in ArcGIS Online and ArcGIS Enterprise.