GIS | Remote Sensing | Cartography | Web Services

Quick & Easy JSON from ArcGIS REST Service

by wolfmapper

I was recently hunting for a way to bring REST services into QGIS, and discovered this post on the QGIS hub. It led me to discover that retrieving JSON from a REST service is much easier than I had imagined. Simply append the following to the end of a service layer URL: query?where=objectid+%3D+objectid&outfields=*&f=json. Copy the full path and paste it into your browser to see the JSON in all its glory!

We’re All Travelers – Entrepreneurship and Transportation

by wolfmapper


On Tuesday, July 29th, the Young Professionals in Transportation held a panel discussion on Entrepreneurship and Transportation at the Code for America office in San Francisco. Included in the panel was Ryan Croft from TransitScreen, Kit Hodge from Vie Bikes (previously of the SF Bicycle Coalition), Jerry Jariyasunant from Automatic, and Fehr & Peers‘ Matthew Ridgway. YPT’er Andy Kosinski kicked things off. The panel discussed various topics related to being entrepreneurs in the field of transportation, from the challenges of starting your own company to balancing creativity to business savviness. Entrepreneurship in the public sector was  also explored, as well as how activism and issues of equity can be addressed when studying and working in transportation.

Some insights and pieces of advice from the speakers:

  • It’s important to have a support system and a team of strategic advisors as an entrepreneur.
  • Entrepreneurship is different between large and small organizations. Large organizations tend to change more slowly, but also tend to be more robust.
  • One of the unique things about being an entrepreneur in transportation is that transportation is something everyone understands. That personal understanding of transportation adds a lot of nuances when designing transportation services/products and understanding transportation needs.
  • A good thing to ask yourself when you’re going through the process of innovation: Am I building something that people want?
  • Starting a company can be an emotional roller coaster.
  • Listen to your early customers.
  • Persevere.

Each speaker had a thought to share about the future of transportation. Here are some of the big ideas:

  • The end of street parking is near.
  • We’re going to see fewer personal vehicles in the future.
  • Cargo bikes will gain in popularity.

Looking for Spatial Data?

by wolfmapper

For the past few years, I’ve been keeping a list of free spatial data I find online. I shared this list with a fellow maptimer, who commented that they weren’t aware of any other list like this. Well, I’m sure there are others who are keeping their own lists, but I thought it couldn’t hurt to post!


Alameda – Contra Costa Transit District

Alameda County Geospatial Data Files

Bay Area Automated Mapping Association

Bay Area Digital Elevation Models


California Geoportal

Code for Oakland Data  

Community College Enrollment

Fresno GIS

Metro Developer (LACMTA)

Metropolitan Transportation Commision


SACOG GIS Clearinghouse

Sacramento County GIS Data Library

SANBAG GIS Data Library

San Diego GIS (SANGIS)

San Francisco Data

San Joaquin County GIS Data Download  

Stockton GIS  

Yolo County Data Downloads  

United States

Atlas of Historical County Boundaries


EPA Environmental Dataset Gateway

EPA Smart Location Database


Longitudinal Employer-Household Dynamics (LEHD)

School Attendance Boundary Information System

USGS Water Resources

Earth Explorer


Census TIGER Data

National Historical Geographic Information System

Resources for Mapping Census Data  

Remote Sensing

Global Land Cover Facility

Landsat 8

NAIP Imagery



GIS User’s Guide to Locating and Downloading Free USGS Data

GeoBase (Canada)

National Weather Service

Mid-America Regional Council GIS Data

Natural Earth

NOAA Climate Data Online

NYC DOT Data Feeds

NYPL Map Warper

Old Maps Online

Open Topography

Open Street Map

OSM Data Extracts  


Data Wrangling Handbook

Get the Data

General Transit Feed Specification


Highway – Rail Crossing Inventory

List of Public Transit Agencies with Open Data  



National Transit Database

NOAA Climate Data Online  

North American Transportation Statistics Database

Open Data Handbook

Open Oakland

Public Data on Google

San Francisco Data

San Francisco Estuary Institute  

Washington State Climatology

Using the In-Memory Workspace in ArcGIS

by wolfmapper

The in-memory workspace is a dedicated “scratch” workspace for ArcGIS where geoprocessing outputs can be written. This includes processes run via ArcMap, Model Builder, and Python. Writing data to the in-memory workspace can save heaps of time when compared to writing to disk, especially for long-running applications that involve many steps or iterations. I recently developed an ArcGIS script tool that creates separate OD cost matrix tables for over 500 origin locations and produces a raster allocation surface of results within a study area around each location. When writing the temporary data to a disk location, each origin location analysis required about 72 minutes to complete. With over 500 origins, I could anticipate this would take about 600 hours total to complete (about 25 days). When I switched to using the in-memory workspace, this process was cut down to 6 minutes per origin location (about 50 hours total).

That saves about 23 days of processing time!

Click here to learn more about using the in_memory workspace.

ArcPy Quick Tip: Find Unique Values in a Field Using the Python Window in ArcMap

by wolfmapper

Arcpy Search Cursors can be used in ArcMap to retrieve a list of unique values for a field in a feature class. You can retrieve a list of unique values by following the steps below*:

  • Open the Python window in ArcMap by going to Geoprocessing > Python.
  • In the Python window, enter the code below with the layer name and field name for which you’d like to retrieve a list of unique values.
    • with arcpy.da.SearchCursor(“Enter Layer Name Here”,”Enter Field Name Here”) as cursor:
  • When you hit the enter key after typing this statement, you will be prompted by ‘…’, indicating you can enter more code. Copy and paste the code below into the window:
    • print sorted({str(row[0]) for row in cursor})
  • Hit enter twice to see a list of unique values. 

*This process is a variation on the script shown in this blog post – thanks ArcPy Cafe

2014 Reading List

by wolfmapper

Oberiu: An Anthology of Russian Absurdism an oldie but goodie I keep coming back to by Eugene Ostashevsky

Statistics Done Wrong looks like it could be full of good advice by Alex Reinhart

Tubes: A Journey to the Center of the Internet heard a great interview on NPR with author Andrew Blum

The Beginning of Infinity the mysterious ways of the Internet led me to this one by David Deutsch

The Death and Life of Great American Cities as I learn more about planning, this one keeps popping up by Jane Jacobs

Using Python for Efficiency and Innovation with ArcGIS

by wolfmapper

Yesterday I had the pleasure of talking about one of my favorite things (Python!) with CalGIS organizer Jeff Orton, ArcGIS Desktop product manager Rob Elkins, and a friendly crew of attendees who logged in for the fourth CalGIS webinar leading up to the conference next April in Monterey.

You can download my PowerPoint presentation here: CalGIS Webinar #4Click here to visit the CalGIS website, or watch the webinar below!