Comments on: Olson code timezones geekery http://blog.makerlab.org/2009/05/olson-code-timezones-geekery/ Go on, be curious Wed, 06 Jan 2010 19:06:40 -0800 hourly 1 By: anselm http://blog.makerlab.org/2009/05/olson-code-timezones-geekery/comment-page-1/#comment-779 anselm Wed, 20 May 2009 23:53:50 +0000 http://blog.makerlab.org/?p=712#comment-779 Didn't benchmark. I guess it would be something on the order of 50 instructions in assembler? There might be a page fault or two if the entire thing was memory mapped... It operates in linear time... It won't be as accurate as a vector test unless the resolution of the raster exceeds that of the vectors... I'd benchmark it if there was any conceivable contender for a faster solution :-). Note I should credit Theo Deraadt for suggesting the approach. Didn’t benchmark. I guess it would be something on the order of 50 instructions in assembler? There might be a page fault or two if the entire thing was memory mapped… It operates in linear time… It won’t be as accurate as a vector test unless the resolution of the raster exceeds that of the vectors… I’d benchmark it if there was any conceivable contender for a faster solution :-) . Note I should credit Theo Deraadt for suggesting the approach.

]]> By: Ralf http://blog.makerlab.org/2009/05/olson-code-timezones-geekery/comment-page-1/#comment-778 Ralf Wed, 20 May 2009 23:25:22 +0000 http://blog.makerlab.org/?p=712#comment-778 yeah, me too. did you benchmark a little? Your solution sounds so interesting. That's why i am interested in the average speed of your look up. I am on a 2.8 GHz Intel and once the tree is build up, a look up takes appr. 0.102279 milliseconds. And, do you get the same error for some locations around coastlines? The above given location is not in any time zone from the shapefile!??? Thanks! Ralf yeah, me too. did you benchmark a little? Your solution sounds so interesting. That’s why i am interested in the average speed of your look up. I am on a 2.8 GHz Intel and once the tree is build up, a look up takes appr. 0.102279 milliseconds.

And, do you get the same error for some locations around coastlines? The above given location is not in any time zone from the shapefile!???

Thanks! Ralf

]]> By: anselm http://blog.makerlab.org/2009/05/olson-code-timezones-geekery/comment-page-1/#comment-776 anselm Wed, 20 May 2009 22:20:01 +0000 http://blog.makerlab.org/?p=712#comment-776 Thanks! I have a hard time imagining how to make it faster - it is just a bitmap peek.... Thanks! I have a hard time imagining how to make it faster – it is just a bitmap peek….

]]> By: Ralf http://blog.makerlab.org/2009/05/olson-code-timezones-geekery/comment-page-1/#comment-775 Ralf Wed, 20 May 2009 22:09:09 +0000 http://blog.makerlab.org/?p=712#comment-775 wow. i like your solution with the colorpleth. did you run any benchmarks on this? how long does a lookup take? i was struggling exactly the same problem a few days ago. i am using a prtree and feed it with the timezones polygons. i am using the same shapefile, which is sometimes kinda inaccurate (check this lat/lon: 28.4051872, -80.6058589). do you get the same error? for this, i use a function that calculates the standard time zone (not political, no DST!): http://home.tiscali.nl/~t876506/Multizones.html#iw nice work! ralf wow. i like your solution with the colorpleth. did you run any benchmarks on this? how long does a lookup take? i was struggling exactly the same problem a few days ago. i am using a prtree and feed it with the timezones polygons.

i am using the same shapefile, which is sometimes kinda inaccurate (check this lat/lon: 28.4051872, -80.6058589). do you get the same error? for this, i use a function that calculates the standard time zone (not political, no DST!):

http://home.tiscali.nl/~t876506/Multizones.html#iw

nice work! ralf

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