Summer seems to have arrived, at last.
As you may have noticed, today’s comic contains an algorithm for converting dates into local coordinates. For a given day, you can calculate what that day’s coordinate is for your region. Dan has put together a tool for calculating a day’s coordinates and show it using Google Maps. Note that you can’t calculate a day’s coordinates before the stock market opens on that day (about 9:00 EST) — except for weekends and holidays, when it uses the most recent opening price.
We’ve been having fun trying to reach these coordinates for some time now, when the coordinate is reachable — that is, when it’s not over water, in a military base, or in the middle of Bill Gates’s house.
If you happen to be looking for somewhere to go, driving to the coordinates can be an adventure. If you do, please take pictures and drop them on the geohashing wiki (feel free to help fill it out). I’m gonna get some rest and then, at 10 AM tomorrow, see if I can get to the Boston coordinates (I have no way of knowing where they’ll be until then, of course).
And finally, when the coordinates are reachable, meetups are Saturday afternoon at 4:00.
Edit: I answered a bunch of questions in a comment below. Further discussion is also happening on the wiki. I’m going to get some sleep and then head out to today’s coordinates (or as close as I can get).
xkcd 
I look forward to wacky adventures and interesting experiences with fellow #xkcd members 😀
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I doubt I will find anyone in my area ='(
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No… We’ll find you.
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And I don’t know how I managed to double-post with a CAPTCHA.
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I have to leave a response, because the captcha is my name (twice, it’s Tim Timothy), and I’m very creeped out.
Geocaching for people, huh? What do we do? Wear black hats and bring signs for nerd sniping?
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Tennessee Valley? That’s where my high school ran cross country meets. Too bad I’ll be on a plane home from Boston.
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I’ll bring Twister.
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Is there a way to adjust the algorithm so that the meetup point never appears over water?
This algorithm is the reason Osama bin Laden is still alive.
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> Tennessee Valley? That’s where my high school ran cross country meets. Too bad I’ll be on a plane home from Boston.
There’s one in every region (graticule), so whenever you’re free on a Saturday, check out where it is!
> I’ll bring Twister.
I’ll bring the Crisco.
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> Is there a way to adjust the algorithm so that the meetup point never appears over water?
Not without making it a lot more complicated. We don’t need a meetup every day, and you can always go to the one nearby if there are problems.
> This algorithm is the reason Osama bin Laden is still alive.
This algorithm also killed Jeeves.
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Yeah, I can’t seem to make it work. I’m either doing something wrong, or the map’s being weird. Any and all help welcome.
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It really doesn’t work well for the DC region, since four different graticules seems to be centered right on the city. So, the likelihood is a very long drive from any point in the city, not to mention the population center being split into four different areas.
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I am in Tokyo right now. By the time 9AM EST hits, it will be 10PM here. basically I will not know the coordinates of where to meet until after the trains slow down. I’d like to think that I am not the only person in the area who reads XKCD and would definitely love to try this out. Any ideas or suggestions?
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Note: Works amazingly well for the Orlando area.
I’ll be hitting up Saturday meetings.
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umm, this doesn’t work for cities where folks typically can’t easily travel farther than typical public transit range
eg for NYC, the location chosen SUCKS in terms of percentage of folks who’d find the location feasibly reachable
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Phoenix is split almost straight down the middle between two graticules, and both are filled almost entirely with desert wilderness. At least it’ll be easy to find the xkcd’ers that way. I look forward to seeing how this turns out. : -)
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I can already tell it’s going to be a bitch for Seattleites. About half of the spots are going to require a ferry trip, and that’s excluding Puget Sound, which rudely consumes about 25% of the surface area.
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So when’s everyone planning on meeting up?
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saturday?
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For those of us in the regions bordering Lake Michigan, where the defined box contains a tiny slice of coast and a giant swath of lake, it’s going to be a rare day where this particular geo-hash doesn’t require a boat or a plane. Or a seaplane. Which would be awesome.
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HEADS-UP: In the Degree Minutes Seconds version of the online implementation (third line), the Seconds portion sometimes appears as a large negative number, certainly not between 0 and 59.9999. Might want to check it out. Other than that.. love the concept! Will try to meetup!
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> I am in Tokyo right now. By the time 9AM EST hits, it will be 10PM here.
> basically I will not know the coordinates of where to meet until after the
> trains slow down. I’d like to think that I am not the only person in the area
> who reads XKCD and would definitely love to try this out. Any ideas or
> suggestions?
Similar problem for Sydney, where it’ll be 11PM.
Of course, it doesn’t affect the Saturday afternoon meetup, ’cause it uses Friday’s opening price. I figure the simple answer is to stick to Saturdays.
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The link to this page from the comic is broken… it’s http://blag.xkcd.com/geohashing/2008/05/21/ when it should be http://blag.xkcd.com/2008/05/21/geohashing/
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> For those of us in the regions bordering Lake Michigan, where the defined box contains a tiny slice of coast and a giant swath of lake, it’s going to be a rare day where this particular geo-hash doesn’t require a boat or a plane. Or a seaplane. Which would be awesome.
While I am all about the seaplanes, we’ll see if we can’t figure out a special case for those unfortunately-located cities. One thing you can try is going to the coordinate for the bordering zone.
On the other hand, seaplanes!
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I started to write down all my ideas to improve this algorithm but I realized that after doing any one of them it became impossible to meet anyone. Guess I just like going random places all by myself.
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>I can already tell it’s going to be a bitch for Seattleites. About half of the >spots are going to require a ferry trip, and that’s excluding Puget Sound, >which rudely consumes about 25% of the surface area.
And if those two facts weren’t bad enough, the graticule covers very heavily populated area – like today’s location is in some backyard in a residential area. We’ll just have to hope that most Saturdays we’ll get lucky and it will be a park or some public location on the east side!
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The Boston area meetup looks to be in a grove of trees in West Bumfuck, MA, so if the area remains vaguely the same for Friday, it should be pretty interesting finding parking, at least.
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http://irc.peeron.com/xkcd/map/map.html?date=2008-05-20&lat=28&long=-81&seed=null&zoom=16&abs=1
Some of these are remarkably interesting.
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For those of you with your city split by multiple graticules, I suggest coming to consensus about which one you’re going to use on the wiki and then just sticking to it. Set up a page for your city and discuss, plus you could use it for RSVPing meetings the night before!
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this past weekend, when i entered May 16th in the tool thingy, the meeting spot was a three minute drive from my house in my region. is there any sort of repeating pattern in this algorithm or is that a stupid question?
way not to post this a week sooner, i’d have definitely been there. dammit.
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The comic probably contains the location for the next XKCD meetup. Better bookmark it.
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>eg for NYC, the location chosen SUCKS in terms of percentage of folks who’d find the location feasibly reachable
On the other hand, if you venture out onto Long Island (train ride away), pretty much everyone there has at least one car available to them.
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I would love to know if there are any other Baltimorons who read this. Maybe we can all go out and get coffee. If there are any others, that is.
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So, the blog (er, blag) says that the time is 4pm, while the Wiki says it’s 3pm. Which one’s official?
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wait, were those example coordinates where Randall lives?
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Actually, there is a problem with the algorithm (mentioned above), if you are close to a line it tends to only send you away from the line, it sorts of repels the line.
Since I am just by the sea, this is a bit of a problem, since it tends to put me into the ocean. It’d make more sense, from my point of view to instead say multiply by 2 and subtract 1 from the post-md5 base-10 converted value (I know, that doesn’t give you the true full range, but you can use say the last digit as a sign bit if you prefer).
Of course, for towns with special requirements you could always mandate a signbit or offset to avoid the water/etc.
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Brendan: No, Randall lives in Cambridge.
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This is awesome but my idea for the solve the “water” and “farmer’s field” problem is to “march” to the nearest Mcdonald’s, Wendy’s or Tim Hortons (if you are Canadian)…or park if you prefer…the dedicated would probably go where ever for XKCD others…maybe not.
Anyway the main meeting would be at this place while the others would walk…anyway that is my idea…how to organize it simply is impossible.
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Why not treat a hash over water as a collision? Just re-generate a hash as the addition (or XOR) of the original md5 hash and the previous day’s hash to get a new offset. There could be a “collision detected” button on the page to let the server know if the location looks like it’s over water.
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So, uh, it requires your starting co-ordinates.
Doesn’t this mean that if people don’t use the same starting location we’ll all end up in different places?
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For two reasons already mentioned, this is tricky for Chicago. Because the whole-degree lines run through or close to the city, there are four different zones that one might initially consider. The northeast zone is probably 80-90% Lake Michigan, a bit of the north side of the city, the north suburbs, and into Wisconsin. The southeast zone goes fairly far south of the city. The western regions, both north and south, don’t really hit the city so much as the western suburbs, but they both extend well past exurbia into rural Illinois and Wisconsin.
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Darn. I live on Lake Michigan, and most of the box spreads on the lake.
And I echo Jenny’s question. It says 3 on the wiki, 4 on the blag. Why?
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Mine is right in the middle of the water.
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I can’t get the map gizmo to work. When I click on it, it shows a red rectangle (presumably the relevant map region), but as far as I can see there’s nothing inside the rectangle to mark any particular point. Help?
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Because of the time zone difference, if you use the tool in Asia, Australia, New Zealand, etc, the map tool doesn’t work with today’s date. You have to use the previous day’s date, because most of the time it’s still yesterday in America.
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Randall: if the location is in water, just append a prime/apostrophe to the end of the original date/stock string, and re-hash. You should be able to just add a button that says “click here if that site was in the water” which fixes the problem that way.
Also, why did you choose 2005-05-26? (I know why *I* might have chosen it, since it was a particularly memorable birthday party for me, but I have no idea why *you’d* have chosen it.)
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Someone who lives on the coast and and has lat/lon coordinates bordering whole numbers might have to do alot of scuba diving. It turns out somewhere around Santa Cruz (36.99, -122.01) … oh, wait… NOW I get why the map starts out centered on the bay area!
(actually, i’m not totally sure if it’s not just because google maps likes to default to the bay area. i hope not, that always annoyed me a little)
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>Because of the time zone difference, if you use the tool in Asia, Australia, New Zealand, etc, the map tool doesn’t work with today’s date. You have to use the previous day’s date, because most of the time it’s still yesterday in America.
Yes, but as mentioned earlier, meetups are on Saturdays. Since the market is closed on weekends, the algorithm already uses the previous day’s (Friday’s) numbers to calculate the position.
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The most recent target for my region is right next to a tiny little beach I went to by accident last time I was on holiday. This is about 60 kilometres out of my city, so it’s surprising that I know the place!
Ross, have you entered a date (and maybe hit Update too)? It should show a little google map marker on the chosen spot for that region, as well as give the lat/long in a box in the bottom right.
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