RE: FN-FORUM: Postcode Radius Search

date posted 31st March 2008 17:18

I think I've managed to do it albeit a postcode square:

This is how I believe the calculation works.

Target Postcode = postcode from which to create the radius search
Search Radius = number (i.e. 30 miles)
LatitudeIncredment = Calculation (SearchRadius * .01446861 //degrees per
mile)
LongitudeIncrement = Calculation (SearchRadius * .01446861 / Cos ( Radians
( TargetLatitude ) ))


WestLongitudeBounds = Calculation (TargetLongitude - LongitudeIncrement)
EastLongitudeBounds = Calculation (TargetLongitude + LongitudeIncrement)
NorthLongitudeBounds = Calculation (TargetLatitude + LatitudeIncrement)
SouthLongitudeBounds = Calculation (TargetLatitude - LatitudeIncrement)

Ive tested it against multimap etc. And another postcode tool I've been
trialing and it brings back a very similar set of results.



-----Original Message-----
From: [EMAIL REMOVED] [EMAIL REMOVED] On Behalf Of Brian
Lycett
Sent: 31 March 2008 18:31
To: FN-FORUM / [EMAIL REMOVED]
Subject: RE: FN-FORUM: Postcode Radius Search


Hi Karl.

The link I gave you has a DB with the first part of the postcode, so a
radius search isn't very accurate as it's going by the whole postcode
area.
So the more accurate your database is, the more useful the results for a
radius search.

If you're after the locations within a radius then the code on the links I
sent you aren't so useful. You need to do it in the SQL query so that you
can limit the result set.
I used the DB in the link I gave you and some disctance calculating SQL I
found elsewhere to create this utility in about an hour (it would have
been quicker if the SQL dump didn't have a stupid bug that I missed).

http://www.wheelybird.com/noncms/postcode/index.php
(that page will only be active for the next few hours).

If you wanted, I could do something like that with your own database. You
didn't say if you wanted it as web application though.

By the way, someone mentioned the legality of the data. You can't
copyright coordinates, but you can copyright an entire database. So as
long as you're using a public domain database or a licensed database, then
there's no legal issue there.

Regards,

Brian.

>
> Brian,
>
> Thanks for this.
>
> I already have 2 files:
>
> 1)
> Just leading in postcode but general UK district coverage I think
> AB10,391978,804275
> AB11,394481,805116
> AB12,389980,799273
> Ca. 3000 records (similar to your link)
>
> 2)
> Full postcodes, but not entire database
> 57.000000,0.000000,AB10 7LE
> 57.145931,-2.165580,AB15 6YJ
> 57.153180,-2.221180,AB15 8UN
> 57.204940,-2.211980,AB21 0GU
> Ca. 3000 records
>
> So I've either got too much info, i.e. AB10 7LE or not enough. i.e.
> AB10...
> it seems
>
> Would this be a separate FM DB and would it need to relate/reference to my
> existing clients DB or would it just bring back the postcode within the
> radius given ?
>
> As I don't need too much detail, just something like this
>
> Search on YO1 (sorted by miles)
> Postcode, Distance (Miles)
> YO1 6, 0.385
> YO1 7, 0.336
> YO1 8, 0.290
> YO1 9, 0.000
> YO10 3, 1.230
> YO10 4, 1.276
> YO23 1, 1.029
> YO24 1, 1.377
> YO24 4, 1.440
> YO26 4, 1.245
> YO30 6, 1.517
> YO30 7, 0.796
> YO31 0, 1.299
> YO31 1, 1.525
> YO31 7, 0.529
> YO31 8, 1.028
> YO31 9, 1.688
>
> How much would you charge to create this ? if you can...
>
>
> Karl
>
> -----Original Message-----
> From: [EMAIL REMOVED] [EMAIL REMOVED] On Behalf Of Brian
> Lycett
> Sent: 31 March 2008 16:22
> To: FN-FORUM / [EMAIL REMOVED]
> Subject: Re: FN-FORUM: Postcode Radius Search
>
>
>
> Getting the database is the hard part. The calculations are easy: try
>
http://www.pjenkins.co.uk/blog/index.php/2007/04/04/uk_post_code_distance_ca
> lculation/
>
> The records without the longitude/latitude will be pretty useless for
> this.
> http://www.linuxbox.co.uk/postcode_database.php has a cheap-ish and
> reasonably complete database.
>
> Regards,
>
> Brian.
>
>>
>>>
>>>
>>> Hi everyone,
>>>
>>> I've spent a lot of time looking at potential solutions and wanted to =
>>> find
>>> out if anyone on here can build/develop a quick and easy postcode
>>> search
>>> tool.
>>>
>>> I'm trialing a piece of software screen below:
>>>
>>> http://www.architecturalselect.com/assets/docs/screen.jpg
>>>
>>> this returns postcodes within a certain radius either sorted by
>>> distance
>>> =
>>> or
>>> by postcode.
>>>
>>> I currently have a 3800 db set of postcode records which holds the full
>>> postcode / longitude and latitude coordinates and have access to others
>>> which only hold the postcode in part, i.e. bs1.
>>>
>>> At the minute I don't mind if it's a separate app or a spreadsheet etc
>>> =
>>> but I
>>> would like to be able to have something that is searchable.
>>>
>>> Can anyone in here build something like this ?
>>>
>>>
>>>
>>>
>>> Regards,
>>> =A0
>>> Karl
>>>
>>> Karl McClelland
>>>
>>> Architectural Select Ltd.
>>>
>>> [EMAIL REMOVED]
>>>
>>> +44 (0)7894 552 671
>>> +44 (0)1761 410 704
>>> Skype | karl.mcclelland
>>>
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