Display a web map | ArcGIS for Developers

ArcGIS DevLabs Python Maps & Layers

Overview

You will learn: how to use the ArcGIS API for Python to load a web map for display.

An ArcGIS web map is an interactive display of geographic information composed of a basemap, web layers, and other supporting information to help reveal data and patterns as you interact with it. Visit the product documentation for web maps to get a complete overview.

In this lab you will search ArcGIS Online for an existing web map and display it using the ArcGIS API for Python.

Before You Begin

The ArcGIS API for Python DevLabs use Jupyter Notebooks to execute Python code. If you are new to Python, please see the ArcGIS API for Python guide to Using the Jupyter notebook environment.

Steps

Display a web map with the ArcGIS API for Python

Go to the Esri Juptyter Notebook and click New > Python 3 to create a new notebook.

You will run this lab in a Jupyter Notebook IDE that is hosted by Esri. Notebooks created here are temporary, hence you must download them if you want to preserve them for later. However, you can install the ArcGIS API for Python locally on your computer and run this lab from it, in which case, the notebooks are stored locally on your machine.

In each step below, type (or copy and paste) the commands into a new notebook cell and run the code by clicking run cell or pressing shift + Enter.
Add the following code in a cell to import the ArcGIS API for Python.

Import python modules written elsewhere for use in your notebook with the Python import statement. If you run this lab from the Jupyter Notebook hosted by Esri the modules are set up and ready to use. If you run this project locally you must install the ArcGIS API for Python and any modules not in your environment.

arcgis.gis is the ArcGIS API for Python GIS model.
```
from arcgis.gis import *
```
Make an anonymous connection to ArcGIS Online.

You can search ArcGIS Online for items shared publicly without logging into your account.
```
dev_gis = GIS("https://www.arcgis.com")
```
You will search for a publicly available web map titled 'LA Parks and Trails Map (sytled with popups)' owned by 'cheangerlove'. It contains datasets about Los Angeles, CA parks and trails. You'll use the wildcard capabilities of the search engine to narrow the search.

The ArcGIS API for Python Guide walks through the process of searching for content. Consult the Search Reference for specifics on how to construct the query parameter for the search method on ArcGIS API for Python Helper Objects.
```
webmap_search = dev_gis.content.search(query = "LA Parks and Trails *", item_type = "Web Map")
webmap_search
```
Retrieve the web map item from the resulting list.

The index for the specific web map may be different in your gis.
```
webmap = webmap_search[2]
webmap
```

Import the WebMap class from the arcgis.mapping module and visualize the web map.

from arcgis.mapping import WebMap
la_parks_trails = WebMap(webmap)
la_parks_trails

Congratulations, you're done!

Your map and layers (feature services) should look something like this.

Challenge

Explore the layers in the Web Map with the REST API.

All hosted feature layers have a REST endpoint that you can use to access the data directly. This can be accomplished with a URL request from a web browser, a custom application, or the ArcGIS APIs.

Let's use the web map to retrieve the layers. You can query the web map as a dictionary.

op_layers = la_parks_trails['operationalLayers']
print("The web map has {} layers.".format(len(op_layers)))

Query the list for the id and url values of each layer.

for lyr in op_layers:
    print("{}\n\t{}".format(lyr['id'], lyr['url']))

In your browser, add the URL for the Trails_7558 layer to the browser (or just copy/paste from below) to explore the REST endpoint:

https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0

Explore the other layers through the same steps.

To learn more about querying data with the REST API, see the Query a feature layer lab.

ArcGIS DevLabs Python Maps & Layers

10 minutes

Requirements

Solution