Open Data Portals

We're gonna take a look at two open data portals and learn how to gather the data, if available, to address our question,

"Where are all the properties owned by the City of LA?"

So where do we go find these properties?

Now properties are recorded and tracked by the Los Angeles County Assessor, a department of the County of LA. The responsibilities of the Assessor include (Source)

• Locate all taxable property in the County and identify the ownership.
• Establish a taxable value for all property subject to property taxation.
• Complete an assessment roll showing the assessed values of all property.
• Apply all legal exemptions.

This map shows all the properties that the County Assessor must manage, this includes all 88 cities and unincorporated areas.

In these assessments, the County Assessor provides information such as:

• The property address
• The name of the owner and their address if not the same as the property
• In the data portals, this information is not available due to privacy issues, but they can be purchased directly from the assessor.
• Publicly Owned parcels, on the other hand are available from the data portals.
• The year the buildings were built
• Land Value
• Use of the property
• And much more!

So we can use assessor's data to find properties owned by the City of LA?

Yes, and we're fortunate that the assessor has contributed their data to the open data initiative that the County of LA started. So let's go find it! Fire up a new tab, and goto data.lacounty.gov

With the county data portal you can get the data without having to create an account. If you filter your data on the portal, you are able to save the results to your account and use it later OR you can have the data directly load to your map without having you host it!

Filtering data means getting user-defined data within a large dataset. The filtering is done through a series of functions like only displaying LA City owned properties in a dataset that has all the properties in LA County.

What do you mean without having me to host it?

For example, there's a dataset in the portal called Locations/Points of Interest. This set contains over 73,000 locations ranging from Arts and Recreation / Community Groups / Post Offices / Social Services and Municipal Service locations. It's a treasure trove of amazing data for making maps!

This is what it looks like on the website

Here you have 3 choices:

1. You can download the entire dataset for use on QGIS
2. You can filter it here on the data portal with your account and download what you are looking for in that dataset.
3. The filtered dataset that you save on your open portal account can be accessed whenever you load up your webmap, be it leaflet or mapbox.js.