Picture Frame That Scrapes Train Times From The Web

January 8, 2013 by Mike Szczys 22 Comments

rpi-train-times-fixture

Whenever [Gareth James] needs to catch a train he has only to push a button on this frame and the next three departure times will be displayed. As you can see from the post-processing in the photo, this is accomplished by a Raspberry Pi board using a few familiar tools.

Let’s take a look at the hardware first. He acquired a 7″ LCD display which he removed from its plastic case. The bare screen will easily fit inside of the rather deep wood frame and its composite video input makes it quite simple to interface with the RPi board. There was a little work to be done for power. The LCD needs 12V so he’s using a 12V wall wart to feed the frame, and including a USB car charger to power the RPi. The last thing he added is a button connected to the GPIO header to tell the system to fetch a new set of times.

A Python script monitors the button and uses Beautiful Soup to scrape the train info off of a website. To get the look he wanted [Gareth] wrote a GUI using tkinter. Don’t miss the demo after the jump.

If you need a bit of a primer on scraping web data take a look at this guide.

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Web Scraping Tutorial

December 10, 2012 by Mike Szczys 36 Comments

Web scraping is the act of programmatically harvesting data from a webpage. It consists of finding a way to format the URLs to pages containing useful information, and then parsing the DOM tree to get at the data. It’s a bit finicky, but our experience is that this is easier than it sounds. That’s especially true if you take some of the tips from this web scraping tutorial.

It is more of an intermediate tutorial as it doesn’t feature any code. But if you can bring yourself up to speed on using BeautifulSoup and Python the rest is not hard to implement by trial and error. [Hartley Brody] discusses investigating how the GET requests are formed on your webpage of choice. Once that URL syntax has been figured out just look through the source code for tags (css or otherwise) that can be used as hooks to get at your target data.

So what can this be used for? A lot of things. We’d suggest reading the Reddit comments as there are several real world uses discussed there. But one that immediately pops to mind is the picture harvesting [Mark Zuckerburg] used when he created Facemash.