[Talk-GB] Postcode data

[Aidan McGinley]

Steve, yes you're right that was a typo on my part :)

Here is the full analysis of the problematic ways

61130908 SW2 4RT in OSM vs SW2 4SG from ONS
112682060 in OSM SW1 2SE vs SW1V 2SE from ONS
139941192 in OSM vs SE11 5EN vs SE11 5EF from ONS
116957518 in OSM vs SW1V 1DX  vs SW1P 1JQ from ONS
124038826 in OSM vs SW3 4UD vs SW3 4UJ from ONS
185247746 in OSM vs SW11 6QF vs SW11 6LD from ONS

61130908 can be accounted for as the postcode SW24RT was retired in Dec
2011 and simply has not been updated on OSM, so not an issue
112682060 The postcode SW12SE does not exist, it looks like a typo on OSM,
again not cause for concern
139941192 This is an interesting one.  Essentially it is the SOCA HQ
building.  The published address for SOCA (from their website) is a PO Box
with the postcode as entered on OSM (5EN), I’m assuming the ultimate
destination is this building so if the destination is the basis for a
correctly tagged postcode then it is correct on OSM.  Equally the 5EF
postcode applies to Citadel Place and the building SOCA is in, so I would
say this is an accurate identification by the script and could correctly be
tagged with both.
116957518 judging by the Bing ariel image this building is not mapped
correctly and slightly off from it's correct location, that is a clear
danger of doing the import and an issue I've always been conscious of.
 There is no obvious way to determine whether a building is correctly
aligned without manual inspection.
I'm not 100% sure what the issue with the remaining two are, but at a guess
I would say it is similar to the issue raised by Ed Loach already, namely
residential property that is above a business having a separate postcode to
the business operating beneath it.  Both of these ways represent a
business, however it looks like there are flats above them.  If someone has
any better ideas then would love to hear them.

In summary, there is 3 false positives out of 95 in this sample data.  It
is not going to be possible to remedy the cause of those false positives,
and it's not clear how prevalent the two issues behind them are in OSM -
namely misaligned buildings and multiuse properties.  I'm going to assume
that uncertainty is sufficient reason not to import so will cease work on
preparing the import.

Having said that I'm sure the data is useful so I'm interested in exploring
any ideas the community might have.


On 28 February 2013 16:14, Steve Doerr <doerr.stephen at gmail.com> wrote:

> On 28/02/2013 12:27, Aidan McGinley wrote:
>
>  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.
>>
>
> Hopefully that's a typo for SW152BU?
>
> More importantly, that highlights an enhancement that I'd like to request:
> always make sure the two parts of the postcode are separated, even if they
> are not in the source data. I think this should be easy, as the second part
> is always the last three characters.
>
> --
> Steve
>
>
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