Tip of the Day – Check the Code

Some of the most popular pages on GISDoctor.com (shameless self-plug) are those that provide examples of how to read WMS data into Google Map applications from a number of sources including ArcGIS Server, OpenLayers, and MapServer.  People take the code from these pages, embed the scripts into their own applications, make some modifications, and publish their own mash-ups.  I think this is awesome and I encourage it on the pages themselves.  I’ve seen a few good applications of this code and I hope more come in the future.

However, I need you, the mash-up artist, to make sure you do one little thing when copying the code into your own applications. Do not copy the Google Analytics code into your own page.  This is the last two blocks of script at the end of each page.  To aid the user I have included a comment to remind them to not to include the Google Analytics script in their application.


A few times a week I notice pages that have used the code from GISDoctor.com (second plug of the post) that still include my Google Analytics information.  Most of the time the user will eventually remove the code or embed their own tracking info, but there are hold-outs.  I’m talking about you, person in Spain.

Thanks, and happy GIS-ing!

Everything Should be Mapped – Somerville Tax Liens

I came across an interesting dataset the other day while reading the Boston Globe (online of course, does anyone buy actual newspapers anymore?).  The story, originally from Ward 5 Online, was discussing the number of properties in my current hometown, Somerville, Massachusetts, that have tax liens over 10,000 dollars!  The article provided a table from the City that included the address, owner name, and amount in back taxes for each property.   The story reported that this data was made available by the City’s aldermen through a request regarding derelict buildings that were shedding bricks (yikes!).

After I read the story I started to search for some of the properties to see if they were in my neighborhood.  I quickly realized that this data would be better utilized if it were in a map.  Thanks to Google Fusion I was able to quickly modify the table and map the addresses and back tax balances.  In the map I created I only included the amount owed, the location, the status (many of the properties have been taken over by the city), and the number of years that the property is late on their taxes.

Back Taxes Legend:  10k to 15k 15k to 20k   20k to 25k   >25,000k

This data can be further analyzed with a number of other free datasets including census, income, or home sales data.  One could then perform any number of analyses to see if there are any spatial patterns in regards to these large tax liens throughout the City (aka, future blog idea).

Also, this map is not perfect.  We all know that there are limitations to mapping with Google, especially in reference to thematic mapping, but overall one cannot complain about the speed and efficiency of creating a simple, but effective map with Google Fusion.  One item I would like to see from Google would be an embeddable legend.  Esri’s JavaScript API can do it, why can’t Google’s?  Now, we can have a discussion about how Google is collecting all of this data, having us create it for them(for free), and then doing who knows what with it, but that is for another day (aka, another future blog post).

Over the next couple of days I will take my dataset over to GeoCommons and work with their tools to create a better map and perhaps do some analysis (aka, another future blog post).

Until next time…

Sweet 2010 Census Mash-Up

My hard-working friends at the Connecticut State Data Center and the Map and Geographic Information Center (MAGIC) at the University of Connecticut Homer Babbidge Library have started to post data from the Wednesday March, 9th release of the 2010 census data for the state of Connecticut.  Talk about a quick turn around!

One of their most interesting 2010 Census Google Map Mash-Ups on their site displays dual-linked Google Maps, with one map displaying the 2010 Connecticut census results by town and the other the 2000 Connecticut census results by town.  The dual-linked maps are synchronized, meaning that movement one map happen on the other.  The user also has the ability to search for their town, or download the data for their own use.  The user can also click on a town and view a table of census data to see how population has changed across Connecticut.  I’m looking forward to what other mash-ups they roll out over the next few days.

Take a look at their site.  MAGIC has been around for a long time, and they have always been innovators in their field.

CTSDC Dual Linked Maps - 2010 Census
CTSDC Dual Linked Maps - 2010 Census

and…quick disclaimer, I helped write the code for the underlying mash-up.  That’s it, they did the rest and they did a great job.