You will learn: how to use the Map Viewer analysis tools to find and extract features.
ArcGIS Online includes a powerful set of tools for analyzing and managing data. When preparing data for an application, a common task is to extract a subset of data from a larger dataset using a spatial query. For example, you might want to define a SQL query to extract features by attribute value or a spatial query to extract features that intersect. Using the Map Viewer you can use the Derive New Locations and Find Existing Locations spatial analysis tools to perform these types of operations. Both tools require an expression that contains one or more attributes or spatial queries to filter the data. The result of the operation is a new hosted feature layer that contains a subset of the original data.
In this tutorial you will use the Find Locations tools to extract a subset of data from the Trails and the USA Zip Codes layers for the Santa Monica Mountains area.
Go to the LA Parks and Trails Map web map and click Sign In.
Click Save > Save As > Save Map to save a copy.
Use the Derive New Locations tool to create a new layer that just contains the Backbone trails.
In the top bar, click Analysis.
In the panel, click Find Locations > Derive New Locations and select the following:
Uncheck all of the other layers so just the new Backbone Trail layer is visible.
In the top bar, click + Add > Search for Layers:
USA Zip Code Boundaries 2016
Living Atlas Layers
In Contents, click United States ZIP Code Boundaries 2016 > ... > Move Down to move the layer under Backbone Trail.
Use the Find Existing Locations tool to create a new layer that only contains the zip codes that are within 3 miles from the Backbone Trail.
In the top bar, click Analysis.
In the panel, click Find Locations > Find Existing Locations and select the following:
Zip Codes layer below the
Backbone Trail layer.
Uncheck United States ZIP Code Boundaries 2016 layer so the new layer is more visible.
Improve the visualization for the new Zip Codes layer by classifying it by populuation.
Click Zip Codes > Change Style and select the following:
In Contents, click Show Map Legend.
Click on the map to explore the lowest and highest populations in zip code areas near the trail.
Save the map.
Your web map should look something like this.
Use the Map Viewer to create a Map Notes layer and manually draw a polygon graphic that can be used to extract a subset of the Trailheads data. The polygon should represent an area that overlaps with the Trailheads you would like to extract.
Learn more about how to create Map Notes and graphics in the Draw graphics tutorial.
Click + Add > Add Map Notes > Create to create a new Map Notes layer.
In Add Features > Map Notes - Areas select Area.
Find the Mahou Riviera peninsula and click on the map to draw a polygon that encompasses some trailheads.
Click Close to save the graphic and Edit at top to stop editing.
In the top bar, click Perform Analysis.
Click Find Locations > Find Existing Locations and select the following:
Mahou Riviera Trailheads.
This should create a new layer that contains the Trailheads that fall inside of the Map Notes polygon graphic.