In my last blog post I counted up the number of pubs provided within CloudMade's (25/11/09) OSM export and compared them to the number of pubs we're told that exist within the UK; in short, about 38% of UK pubs are in OpenStreetMap. I got some really great comments on that last entry  and was looking forward to the next release from CloudMade to see the rate that UK pubs were (hopefully) growing.
Gregory Williams posted some interesting numbers drawn directly from the database, rather than my CloudMade numbers. He looked for pubs and bars and found 22523 and 350 respectively; I was hoping that this number represented a big increase in recorded pubs, perhaps indicative of the rate at which the UK is being mapped. I was wrong, however, as the release of CloudMade's 02/12/09 dataset revealed:
joseph@joseph-work:~$ grep -ci '
joseph@joseph-work:~$ grep -i '
(20 742 / 53 466) * 100 = 38.7947481
Whilst the number of pubs recorded in the UK has risen (as with the number of pubs recorded with the word "closed" in their name), the running total still stands at c.38% of the Guardian's figure. It seems then, that Gregory Williams' SQL query was pulling out 2000 pubs from the database that CloudMade doesn't. I think that's quite interesting and possibly something worth looking into. Gregory also notes that 20.7% of UK postboxes are recorded on OSM; I guess we can say that mappers prefer pubs to posting.
This time around I've taken the CloudMade export and plotted the position of OpenStreetMap's record of UK pubs as a simple map:
Gary Jones, our GIS officer, gave me a good run-through QGIS 1.3.0; I imported the CloudMade gpx file, pulled out the pubs and plotted them on top of the coastline export. The pubs as a shape file are available here under the same CC-A-SA-2.0 license as the image above. Apologies for the lack of coastline for the Isle of Man in my image, I tried to add it, but it crashed QGIS and seemed to wreck my saved project file, so I left it be. If anyone else creates any other pub maps, please let me know.
There are certainly gaps in the map above! Is that because there's missing pubs or simply areas without pubs? I guess that's the point of a completeness survey! I can say that there are gaps on the image within which I have certainly enjoyed a pint. Presumably the c.62% of UK pubs that don't appear on the map above are located in both areas that are completely blank and also within partially completed regions. The UK is too big an area to conduct meaningful completeness surveys on; we need official pub number and OpenStreetMap counts for a smaller selection of areas. Perhaps county would be an appropriate scale to start with?
Something to mull over on a dark and cold evening...
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