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Sunday, December 17, 2006

UK Postcode Coverage Map

On a website that I have been making I had to provide a "Find my nearest" page, one of those things where people enter their postcode to find the nearest outlet of the company in question. An easy application of Pythagoras' Theorem using the full UK postcode database that I was provided with.

In a bored moment today though I wrote a short little program to go through the database and mark a dot on a blank canvas for the coordinates of each post code. As can be seen I got a very realistic outline of Britain. Although, I was a bit disturbed by the shape of Wales so I overlayed my data onto a satellite photo of the UK, there does appear to be some sort of a problem, is my database broken?

The satellite overlay does do a good job of confirming that the less postcode dense mainland areas very often correspond to mountainous areas.

Update: Thank you Mapperz for pointing out my mistake (Northern Ireland postcodes work off a different grid system). Seeing as it is not just a simple constant offset between the two grid systems and the company I was making the site for don't have any Northern Ireland outlets, I have just omitted the BT* postcodes from my dataset leaving me with this map.

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  • You need to project the BT (Northern Ireland) postcodes from Irish National Grid to British National Grid.

    That is why you have Postcodes in the Sea and on the land (NW of Wales).


    By Blogger Mapperz, At 8:39 am  

  • Merry Christmas, David, from Christoph and Bear at Loving Jacqui.

    I'll be coming back to your blog after I found a great usable solution here and you helped me customize it further.

    Impressive work with the postal code map!

    By Blogger Christoph Dollis, At 12:29 pm  

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