On Sun, May 6, 2012 at 8:49 AM, Kevin Kenny <kkenny2@nycap.rr.com> wrote:
On 05/06/2012 02:03 AM, Tobias Conradi wrote:
Can you tell a way of how a user determines the correct zone for a random location in Indiana, selecting between
America/Indiana/Indianapolis America/Indiana/Vincennes America/Indiana/Winamac America/Indiana/Marengo America/Indiana/Petersburg America/Indiana/Vevay America/Kentucky/Louisville America/New York
without reading the comments?
Fortunately, nearly everyone in Indiana is aware of the bizarre timezone patchwork. What do you mean by "bizarre timezone patchwork."? Do you mean the existence of eleven zones for Indiana?
Adding to the above eight, these three: America/Indiana/Knox America/Indiana/Tell_City America/Chicago I would assume many people wouldn't know that there are eleven tz zones for locations in Indiana.
The simple rule, "if you're in Eastern time with DST, use New_York, if you're in Eastern time without DST, use Indianapolis; if you're in Central time, use Chicago" is correct for 99% of them, because the breakaway counties are farmland with few inhabitants.
Using http://en.wikipedia.org/wiki/Time_in_Indiana#tz_database and adding up Wikipedia 2010 population data for counties having a tz zone that is not one of the three you singled out, namely Chicago, New_York, Indianapolis, gives: Pulaski 13,402 Pike 12,845 Daviess 31,648 Dubois 41,889 Knox 38,44 Martin 10,334 Crawford 10,713 Clark 110,232 Floyd 74,578 Harrison 39,364 Switzerland 10,613 Starke 23,363 Perry 19,338 SUM 436,759 Indiana population is given with 6,483,802 for 2010. That is the three zones you singled out contain 93.3% of the Indiana population at most, thus cannot be correct for 99%.
Out in the hinterland, it becomes "if you are in one of the half-dozen counties that have their own zones (named like the counties), use that." I see no single zone that is named like a county.
The above county list contains two half dozens and one county. I don't know what you mean by "the half-dozen counties that have their own zones".
If you were to pick a random location on a map in Indiana and ask what time is observed there, I'd be hard pressed to answer. But in that particular case, better mapping might not even help; I was asking for how to determine the tz zone without using the data in the comments, i.e. without any mapping for individual counties at all. Because on Sat, 5 May 2012 04:11:55 +0200 Robert Elz claims:
" erroneous comments are not a bug, as they don't affect the results"
a great many inhabitants and businesses set their clocks to the large cities of Chicago or Indianapolis rather than whatever time their county legislatures have decided to observe that year. Any example for this? It could be added to the tz database and improve the mapping.
If only a minority in a given county does not observe what the law mandates and is in the tz db comments, then having the comments improves the results on average, thus the assumption "better mapping [compared to no mapping] might not help" is wrong. If a majority in a given country does not observe what the law mandates, I would ask on the tz mailing list, whether the information for that area should be changed. -- Tobias Conradi Rheinsberger Str. 18 10115 Berlin Germany http://tobiasconradi.com/