2011/11/19 Hermann Peifer <pei...@gmx.eu>: > On 19/11/2011 13:48, Jo wrote: >>>> >>>> You probably want to add oneway=-1 to that list. There are some >>>> oddballs who used that indicate oneway is against the vector sense. >>>> Also JOSM proposes to use it when reversing a way. >>>> >>>> Jo >>> >>> Thanks for the hint. I already thought about it but forgot to mention >>> that >>> the above tests are using regular expressions. ^motorway also matches >>> motorway_link, etc. and 1 also matches -1. >> >> Is a regex really the best choice for that problem? It's a closed list >> of possibilities (or it ought to be), regexes seriously degrade >> performance in comparison to for instance dictionary lookups (sorry >> for the Python terminology, what I refer to is an unordered datatype >> where one can perform lookups on keys, which are stored in a hash to >> increase performance). When one of the values is outside of that list, >> it should be flagged as an error and be corrected in the data. Or it >> should become part of the list, if it is valid after all. >> >> Just my 2 cents. Regexes are not always the right answer for a problem >> and performance quickly becomes a problem when working with massive >> amounts of data, like what one finds in the OSM DB. > > Thanks for the hint. One could indeed put the oneway values (yes|true|1|-1) > into a hash and have some performance benefit from that. In my case, the > real bottleneck in the process is actually to download the OSM extracts from > Geofabrik, which takes about 10 times longer than the script run... > > About the closed list of possibilities: OSM Mappers are pretty creative and > the value list for a simple key like oneway is not as closed as one might > think: http://taginfo.openstreetmap.org/keys/oneway#values > > On the other hand: the 5 most popular oneway values cover 99.9+ %.
Most of those should simply be corrected and if it's undefined, then why even mention it? Those can simply be removed... Jo _______________________________________________ Talk-de mailing list Talk-de@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-de
