I haven't had time to do the analysis yet Robert, I've been focussing on fixing the issues I've already identified, once they are done I'll do something more detailed. But at a high level these are the numbers:
95 total buildings with an existing postcode tag (after removing ways mapped to more than one postcode) 77 of these match exactly the postcode tag identified by the script (ignoring whitespace) 12 of these buildings only have the first part of the postcode. All of these partially match what is output by the script, for example way 5042255 is tagged in OSM as SW15 and the script identifies it as SW15B2U. 6 entries do not match. These are obviously the important ones that need investigation to see whether there is fundamental issues with the import or if there is a valid reason for the mismatch like typo or postcodes no longer in use. If it turns out there is an issue with these then obviously the import will have to be shelved. On 28 February 2013 09:51, Robert Whittaker (OSM lists) < [email protected]> wrote: > On 27 February 2013 09:03, Andy Allan <[email protected]> wrote: > > On 26 February 2013 22:08, Aidan McGinley > > <[email protected]> wrote: > >> is the actual output that would get loaded onto OSM. > > > > Please don't load this data into OpenStreetMap. It's not a good idea. > > > 1) The source data appears to be heavily overprocessed. > > 2) The license is unclear > > 3) We don't want to import this stuff anyway > > +1 > > As I said before when this was first raised: > > I'm not sure I see much benefit to the import. It's presumably going > to add relatively few postcodes [as a percentage of the total number > of postcodes in the UK], so won't be that much use for anyone wanting > to use OSM data for postcode look-ups. Indeed anyone wanting to do > that could just as easily use the centroid data directly to map a > postcode to a location, and then use that location to do whatever > searching they want to do on OSM. There is obviously some advantage in > that we'll have more buildings / amenities with properly assigned > post-codes. But because of the relatively low benefit (unless I'm > missing something) I would say that the community should see good > evidence for an extremely low error rate on the import before agreeing > that it would be a good thing to do. > > So what evidence is there for this low error rate? What is the result > of my suggestion to look at buildings where there is an existing > postcode in OSM and your method would have a postcode to assign to > that building? What percentage of those buildings result in a match > for the postcodes and what percentage result in disagreement? (Rather > than just producing some comparison data and asking others to check > it, I would say that the onus is on the importer to come up with the > evidence that the import is going to be accurate.) > > In any case, as Andy says, I think a better use for this data would be > an ITO-OSM-Locator-style view where local editors can compare the data > with OSM and use it that way to help verify / improve OSM manually. > > Robert. > > -- > Robert Whittaker > > _______________________________________________ > Talk-GB mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/talk-gb >
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