426: Geohashing

Geohashing

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Title text: Saturday is game night

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Explanation

This is one of 52 incomplete explanations: explain terminology used in determining location (ie mp5) If you can fix this issue, edit the page!

Geocaching is a sport where you have to find things hidden by other people based on geographical coordinates. Randall has had a similar idea before in 201: Christmas GPS.

Geohashing is a sport created by Randall based on reaching a random location determined by an algorithm that involves the current date, location and Dow opening price.

The algorithm is built in a way that:

• Makes it impossible to plan a meeting in advance - because of the Dow.
• Changes every day.
• Gathers people that are nearby - everyone within the same 1°×1° grid square gets the same position.

The algorithm works as follows: 1) Take the current date in the format yyyy-mm-dd- and append the most recent opening value for the Dow Jones Industrial Average. 2) Pass this sting through the MD5 algorithm. 3) Divide the hash value in half, and convert it to a decimal. 4) Take the integer portions of your current current coordinates and append the decimal hash values.

MD5 is a cryptographic hashing algorithm, and converts plaintext data into a seemingly random 128-bit string. This process has three main properties: it is non-reversible (you cannot generate the plaintext data from the hash), a given sample of data will always produce the same hash value, and two different samples of data should never produce the same hash value.

Originally intended as a joke, there are people which do geohashing regularly. Please see the link to the xkcd wiki above.

Transcript

Date (example): 2005-05-26

That date's (or most recent) DOW opening: 10458.68

[Concatenate, with a hyphen: 2005-05-26-10458.68]

md5: db9318c2259923d08b672cb305440f97

[Split it up into two pieces:]

0.db9318c2259923d0, 0.8b672cb305440f97

To decimal: 0.857713..., 0.544544...

Your location (example): 37.421542, -122.085589

[Combine integer part of location with fractional part of hash:]

Destination Coordinates: 37.857713, -122.544544

Sample Implementation: http://xkcd.com/geohashing/

Trivia

• In response to comic 353: Python, the Python developers implemented the module antigravity in version 2.7+. This module contains a reference geohashing function.

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Discussion

Isn't there an app for this? Or am I just confused? Unpopular Opinions (talk) 18:13, 13 February 2020 (UTC)

There are lots of them for different platforms, in fact. 162.158.203.21 10:02, 11 January 2021 (UTC)

The official implementation (http://xkcd.org/geohashing that redirects to http://carabiner.peeron.com/xkcd/map/map.html) doesn't seem to be working anymore.

There are other implementations, such as https://geohashing.info/ --XXOs (talk) 01:06, 8 September 2021 (UTC)

Should there be a thing about the 30W rule? --XXOs (talk) 01:06, 8 September 2021 (UTC)
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