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People in graticules or regions severely restricted by water might consider a modification to the algorithm that will still coincide with the standard coordinates.

Diagram of the approach
Please avoid using alternatives to the official algorithm unless there is a compelling reason to do so in your locale.
  • Alternative algorithms are appropriate for island regions or small countries without open borders. In such cases, please work towards a clear consensus with others in your graticule on the best alternative method for your region before establishing and publicising your local convention.
  • By using an alternate algorithm where it is not appropriate, you effectively fragment your graticule, reducing the number of people who might come to the same meetup.
The following method is only a suggestion. It may not be suitable for all areas requiring an alternate algorithm.

[edit] Details

  1. Take (a,b) as the standard decimal location.
  2. Take (c, d) = (a % 0.5, b % 0.5) as the half-size location. (% is the mod operator)
  3. New locations:
    1. (c, d)
    2. (c + 0.5, d)
    3. (c, d + 0.5)
    4. (c + 0.5, d + 0.5)

One of those is guaranteed to match (a, b), but one of the other three may be more accessible.

[edit] Ramifications

Would this lead to fragmenting of the geohash community? Perhaps not, since anyone using this technique would likely not be able to make it to the standard coordinates. This approach merely serves as a way of deterministically generating alternate meetup locations when the standard one is unreachable.

Yes, but at the cost of reducing the potential people who might show up? I think using the suggestion system per graticule would make more sense, instead of an institutional solution. Zigdon 18:59, 12 June 2008 (UTC)
Agreed. Local convention can and has worked beautifully in instances such as meetup time in wintry Canberra, Australia. With the soaring cost of gasoline/petrol, formalising an alternative interpretation of the algorithm would definitely encourage others who don't need an alternative solution to just seek out the point closest to them, lessening the chances for a meetup and thus making the "sport" less fun since no one shows up. On the flip side, it would make the "sport" more fun for those areas which actually do need alternatives, as meetups could happen more frequently. It's a delicate issue, one that I think can at least be mitigated by some tweaking of the wording in your warning at top. I'll get on that now; feel free to input. --Tim P 21:55, 12 June 2008 (UTC)
Tweaked. My changes to Template:Alternate algorithm are open for comments and, as this is a wiki, edits. I know it's a little wordy, but I think it's crucially important to the livelihood of the "sport" that we explicitly disclaim the possible ramifications of "taking things into your own hands." --Tim P 22:18, 12 June 2008 (UTC)