Looking for holiday lights? This Harvard grad student created an interactive map of Somerville displays

This display is among the many Adam Tanaka catalogued in Somerville.Adam Tanaka

It wasn’t a light bulb that went off in his head that inspired Adam Tanaka to take on the impromptu project — it was the abundance of holiday lights in his Somerville neighborhood.

“I had been noticing the lights for several weeks,” said Tanaka, a graduate student who is studying urban planning at Harvard University. “But suddenly I thought, ‘You know what?’ ”

Earlier this week, before flying home to his native London for Christmas, the 28-year-old hopped on his bicycle and spent 10 hours over the course of two days snapping pictures of the extravagant light displays all around his community.

Once he hit nearly every spot imaginable — Somerville is kind of hilly and his legs got tired while biking, so he didn’t cover every street — Tanaka uploaded the location data from the photos into an interactive public map, complete with a legend identifying the different types of displays. This way, people can refer to the online document as they take their own personal tours of the decorations.

There’s a few reasons why Tanaka did this: He loves data, he’s studying urban planning, and above all, he’s fascinated by the way Americans celebrate the holiday with moving reindeer, strings of red-green-and-white bulbs, and inflatable Santa Clauses.

“I just find that the culture of Christmas decorations is something really unique to New England, and particularly in Somerville they go all out,” Tanaka said. “Homeowners and residents are decorating their own city in a very creative and inspiring way. Certainly in the UK, I have never seen anything to this degree of civic display.”

Of course, there’s an academic angle to it all as well.

Initially, his idea was to find the best and brightest displays, or the ones with “crazy statues or multiple stories” of decorations. But then Tanaka became interested in the “contagion effect,” as he called it.

“When you have a couple of really crazy ones on a street, does that influence the rest of the people on the block to put up their own lights?” he wondered.

He was also curious about what decorations say about a community: Is there any correlation between the density of Christmas decorations on a particular block and the social capital of that neighborhood? Are they indicators of people’s religion? Are homeowners more likely to put up lights than renters? What’s the most popular display?

“I definitely found clustering. Usually if there was one extremely decorated house on a block, the neighbors decided to step up their game,” he said in a follow-up e-mail. “Another thing I noticed was that often the most extravagantly decorated buildings were not on major thoroughfares, but on little side streets, hidden in the midst of the neighborhood.”

Tanaka said rounding up the photos was the most difficult part. But once he completed the task, the project moved ahead fairly quickly. Because every iPhone or smartphone has an embedded GPS, he was able to extract the geographic information of where a picture was taken and upload it into a map platform.

From there, he went through the photos to classify and color-code each dot on the map. Yellow dots identify standard light displays, red dots are holiday statues, purple is for inflatable displays, and green dots pinpoint laser and projection displays. Users can zoom in on the map to find the street name where particular setups can be found.

While compiling the information was informative, Tanaka was most moved by how the lights seemed to serve as an expression of the community.

“My favorite moments were when you could tell that neighbors living in the same building had collaborated,” he said.

Adam Tanaka put the locations of the lights into an interactive public map, so people can tour the community and see the lights for themselves. Adam Tanaka