Talk:Implementations

Atom feed 30W-compliance

I just added the atom feed and it seems to be 30W-compliant

After some thought, I suppose it would be somewhat compliant. However, in some cases it's too compliant, or compliant in the wrong ways. After 00:00 local time, it automatically switches to the next day, but keeps the old Dow value and rehashes. East of 30W that behavior is desired, since you want to use the previous day's Dow anyway. West of 30W, however, it means we get an "intermediate" hash that's invalid for us. This much has always been a problem with the implementation. Then, sometime after 09:30 ET (I don't know precisely when), it detects the new Dow value and updates the hash... but it does it both west of 30W where it is needed, and east of 30W where it is undesired. In that case, you would get some other "intermediate" using the current Dow with the current day, which isn't what you want. That's a new problem the 30W Rule created.

In summary, it seems to produce invalid hashes between 00:00 (local) and ~09:30 EDT (UTC-4) west of 30W, and between ~09:30 EDT (UTC-4) and 24:00 (local) east of 30W. That is, it's invalid from 00:00-~06:30 in US Pacific Daylight Time (UTC-7), from ~14:30-24:00 British Summer Time (UTC+1) or from ~21:30-24:00 Australia Western Standard Time (UTC+8). I'm not even sure I know what would happen with the feed in New Zealand, where 09:30 USEDT = 01:30 NZST the next day. It'll be even worse come late October/early November, when Australia/NZ switch into DSTand the US switch out... the gap will become 2 hours wider over a couple weeks' time. And of course, these problems are mitigated over weekends, when you have several identical Dow values in a row. Someone should check this out before the weekend, as I'll be busy until Friday 19:00 UTC. If anyone does, and has thoughts, hit me up on my talk page.

Sincerely, your friendly local (global?) 30W-compliance "expert"... --Tim P 15:34, 29 May 2008 (UTC)

I have just updated the feed so it should be 30W compliant. Let me know if it's still a problem. --Xxv 18:03, 30 May 2008 (UTC)

Python-CGI-JSON-o-Rama implementation

Hey so i've made a python version of the reference implementation that returns a JSON parseable object containing the lat/long when given a date, xloc and yloc. It uses the XKCD cache of dow values. I'll put it online in the next 5 mins :D

Here it is, fairly simple actually, hope someone finds it useful :)

Update: I've tried to make it classify the region recommended for a particular day using the euclidian distance of the colour of the image provided by Google Maps

The code is on the link above, tell me what you think :)

SinJax

Cool! I was thinking of making it act as a web service, but for reference implementation it's more important to be simple than useful :) Zigdon 14:53, 21 May 2008 (UTC)

I mostly canabolised yours anyways! :) But yeh here you go. The webservice version returning AJAX from python can be found: - AJAX geohashing - Example using the web service

The implementation also has the ability to tell you whether the particular area is water, park/forest or other. It does this by checking the colour on google maps and doing a thresholded euclidian distance check against the expected colours for those things. Also If its water it tells you its probably not accessible I wanna try to add more features like this, things like rating locations based on food and letting you say how far your willing to travel

Thanks to User:Sigmund Fraud from the IRC channel for the space on his server with python installed - SinJax

I've added my own python implementation to the main page (only 5 lines) -- lilac

_very_ nice, im in awe! Though it must be said my concentration was usability as a web service and the implementation of that imaging stuff. Still. Very nice stuff. I love python :) - SinJax

Added a shell script implementation to the main page (slightly shorter than the Python version; let the flames begin) -- gnomon

deeply awesome; no flames from me -- lilac

${var:x:y} slicing isn't portable, so you should really call it a "bash script" and change the #!/bin/sh. I came up with nearly the same thing:

(echo 16i; echo -n "$(date +%F)-$(GET xrl.us/djiopen | col)" | md5 | sed 's/.\{16\}/0.&p/g' | tr a-f A-F) | dc

On Linux, it's md5sum, which prints a "-" for stdin, but dc happily eats that. Your web interface for getting the Dow data is much better/more flexible than that ganky little shortcut url to Y! Finance (they have historical data in .csv too, but at a different interface so I didn't include it), but consider using sed instead. You only have to fire up one dc at the end of the pipeline which is much cleaner IMO.

To make it print out my full co-ordinates, I created a graticule file:

echo -e '42\n-71' > graticule

and appended

| paste -d'\0' graticule -

to the pipeline. If you wanted it put it in a script file as you have and pass them as args, you could (untested):

| while read f; do echo $1$f; shift; done

I'll stop here before I get any farther offtopic :) --Decklin

Error on page?

Just zooming in and out today gives me random meet up locations, any one else having this issue?

Yes, I am experiencing this as well.

It seems to change everytime the applet is reloaded (refreshed, updated, zoomed, or moved) Is there any one who can fix this?

I'm not seeing this? What browsers are you using? Zigdon 17:48, 23 May 2008 (UTC)

I'm experiencing this problem on IE6. MOE37x3 18:10, 23 May 2008 (UTC)

I get the error in IE7 but not Firefox.--Ahecht 18:57, 23 May 2008 (UTC)

Same here, except I us IE6, not 7. Firefox fixed my woes, though. - MythGuy

I, too, am experiencing this. I used the the alternative locater though. http://geohashing.electronicwar.net/

I hope we can we can get this fixed soon. - MythGuy

With the debugger on, I noticed that "00" is appended to the DOW opening every time I click "Update." This changes the hash each time, creating random locations. Zigdon, we need your help. 16:33, 23 May 2008 (UTC)(James)

Ah. Well this is creating problems for me. I used the alternate locator, got location A, went to my local page to see if others might be planning on coming, saw a different GPS (thus giving me location B), I went to the real map and found that the first location that it pops up with is always the same, so I have three locations now... What do I do? - MythGuy

Gah. Ok, I can reproduce this in IE6. I'll see if I can find some simple hack, but doing browser specific code is evil. Zigdon 21:36, 23 May 2008 (UTC)

Ok, it should be fixed in the (beta) version: http://irc.peeron.com/xkcd/map/map2.html. This will become live once the 30W decision is final. Zigdon 21:47, 23 May 2008 (UTC)

Atom Feed

I noticed yesterday that before the stock exchange data becomes available, the atom feed creates a kind of 'intemediary' geohash using todays date and yesterday's data. This might be intentional, but personally I find that undesirable on weekdays. Could it be modified to show yesterday's date and geohash until data is available? Nicktaylor 14:04, 23 May 2008 (UTC)

I'm currently working on getting an alternative Atom Feed implementation ready for public use (although I think I'm going to wait until the Time Zone issue is resolved). Mine will only update at 09:40 Eastern daily (accounting for DST changes), and uses the irc.peeron.com source for the DJIA, which is updated at 09:35.

I will certainly post it here when it's done, so stay tuned. --Tim P 20:10, 23 May 2008 (UTC)

The time zone issue has been resolved with the 30W Time Zone Rule. I'll continue to work on getting my implementation ready. --Tim P 04:34, 24 May 2008 (UTC)

I don't know if I'll bother with my Atom implementation. I copied your original request at Implementations; I'll keep an eye on it there. --Tim P 05:17, 26 May 2008 (UTC)

Is it just me, or is the shell script borked?

Shell script bombs out for me in two places :(

This:

[[ "$DOW" != +([0-9.]) ]] 

Was always returning true, so exiting the script with a "DOW not available yet.". I replaced that with

[[ -z "$DOW" ]]

to get past it.

then it falls over elsewhere with:

./geo.sh:1: unrecognized modifier `0'
./geo.sh:1: unrecognized modifier `1'
,

For reference, the script reads:

#!/bin/zsh
DOW=$(wget -qO- http://irc.peeron.com/xkcd/map/data/$(date +%Y/%m/%d))
[[ "$DOW" != +([0-9.]) ]] && echo "DOW not available yet." && exit 1
MD5=$(echo -n "$(date -dW30 +%Y-%m-%d)-$DOW"|md5sum|cut -d' ' -f 1|tr a-f A-F)
echo "$1$(echo 10k16i0.${MD5:0:16}p|dc), $2$(echo 10k16i0.${MD5:16}p|dc)"

does it work for other people?

And by the way, is the date modifying in the right place? Shouldn't it retrieve yesterday's dow and caculate with today's date in 30W cases - rather than retrieving today's dow and using yesterday's date for the hash?

I've so far worked out that it's failing on the line:

echo "$1$(echo 10k16i0.${MD5:0:16}p|dc), $2$(echo 10k16i0.${MD5:16}p|dc)"

Better yet, I've further narrowed it further. The parts my system doesn't like are:

echo "$1$(echo 10k16i0.${MD5:0:16}p|dc), $2$(echo 10k16i0.${MD5:16}p|dc)"
                             ^ ^^   ^^                          ^^   ^^  

It doesn't understand the numbers and it reports "command not found" for "dc"

--Psud 08:49, 26 May 2008 (UTC)

I've rewritten the script to incorporate some earlier suggestions I made (they were left on the main page's talk page when the implementations were moved) about portability (you seem to have been bitten by the slicing issue I was worried about). However, you will need to have dc installed no matter what. --Decklin

Shell script implementation

While it runs on sh, ksh, and bash now, it still doesn't work on OpenBSD. If GNU date (which has the -d option) is not detected, I assume FreeBSD's -v is available; OpenBSD doesn't appear to have a comparable feature. Could someone test on OS X? No idea what's there (pretty sure they ship with wget, though).

Super brownie points if you can make it fallback to wget *or* fetch in one line so I can delete that stupid usage warning and have it run on FreeBSD out of the box. --Decklin

Could the user at 63.201.144.114 explain what broke? No math is being done in the shell in any case, and nothing added requires the script to be run under GNU bash instead of any POSIX sh. Extra features are nice, if they can only be implemented in the script itself, but that's an entirely separate issue.

iPhone Implementation

Last night I finished a rough implementation of this to the iPhone 2.0 Beta SDK. Right now it uses your current location and date and then does the math, then gives you a map with the destination address along with directions to there from where you are at. This will be even more useful if the next 3G iPhone come with GPS, until then it uses it's less accurate cellular and wifi location tools to locate you. I plan on adding a way to select your date and your desired graticule as well. Eventually I'll also investigate filtering of the results in watery areas. I can't distribute it currently, but as soon as I can I'll make it available. -- Shakedown

Wrong Market Data for 2008-05-30

The official reference implementation has the wrong market data for Friday May 30.

• Direct future discussion on this topic to Template talk:Expeditions/2008-05-31.
  • This has been corrected. --Tim P 19:12, 30 May 2008 (UTC)

Wrong market data for June 2008 in locations east of -30°

The official reference implementation is attempting to fetch the wrong market data for dates in June 2008 for locations east of -30°.

• For 2008-06-01, it attempts to fetch market data for 2008-06-30.
• For 2008-06-02, it attempts to fetch market data for 2008-07-01.
• For 2008-06-29, it attempts to fetch market data for 2008-07-28.
• For 2008-06-30, it attempts to fetch market data for 2008-07-29.
• For 2008-07-01, it attempts to fetch market data for 2008-06-30 (correct).

Locations west of -30°: tested 2008-06-01, which fetches correct data. Not sure of the extent of the issue, more testing needed. - r0d3n7z 18:07, 30 May 2008 (UTC)

Further testing reveals that the problem is not confined to June 2008, but affects all months with less than 31 days for dates after the 30W rule was applied. Examples:

Date	Market data fetched
2008-06-15	2008-07-14 (wrong)
2008-07-15	2008-07-14 (correct)
2008-08-15	2008-08-14 (correct)
2008-09-15	2008-10-14 (wrong)
2008-10-15	2008-10-14 (correct)
2008-11-15	2008-12-14 (wrong)
2008-12-15	2008-12-14 (correct)
2009-01-15	2009-01-14 (correct)
2009-02-15	2009-03-14 (wrong)
2009-03-15	2009-03-14 (correct)
2009-04-15	2009-05-14 (wrong)
2009-05-15	2009-05-14 (correct)
2009-06-15	2009-07-14 (wrong)

Hope this helps pinpoint the problem. -- r0d3n7z 18:32, 30 May 2008 (UTC)

It works perfectly fine here, and has been all along since the previous problem was fixed.--80.216.129.239 19:49, 30 May 2008 (UTC)

I'm not seeing this problem? What browser/OS are you using? What does the debugging info show when it gets the wrong data? Zigdon 20:05, 30 May 2008 (UTC)

I am experiencing this across several browsers. Screencaps: FF1.5 FF2 IE6 IE7 Debugging info shows an attempt to fetch market data for an incorrect date. -- r0d3n7z 20:41, 30 May 2008 (UTC)