Imagine this...
A map of the UK....
You set your circular cursor to a diameter you want, and then roam over the map.
Any postcodes in that circle are then listed...
Any use?
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What's the best Vs easiest method of searching through this list?
There's 1.8 million records.
I thought perhaps uploading them into a database, then sorting on latitude/longitude, and doing a binary search on the resultant co-ordinates for a location inside the boundary set by the user?
What then though? Some kind of sweep away from that record to find neighbouring postcodes? If I did that for the latitude, how would I then scan on the longitude...?
Would sticking the whole dataset in memory, and then doing a search for all the records starting with a (text) section of latitude and longitude work better?
for instance... for each instance of search("53.12"), search on the line... search("-2.12)
I tried this in VBScript with a 230MB file, and found one of the first, then one of the last postcodes in <.2 second!
set objFS = CreateObject("Scripting.FileSystemObject")
set objFile = objFS.GetFile("post.dat")
set objTS = objFile.OpenAsTextStream(ForReading, TristateFalse)
strSearchThis = objTS.Read(objFile.Size)
wscript.echo "Starting search"
if instr(strSearchThis, "AB101JB") > 0 then
wscript.echo "Found 1"
else
wscript.echo "Not found 1"
end if
if instr(strSearchThis, "ZE2 9TZ") > 0 then
wscript.echo "Found 2"
else
wscript.echo "Not found 2"
end if
PZ_Postcode,PZ_IntroductionDate,PZ_GridRefEast,PZ_GridRefNorth,PZ_County,PZ_District,PZ_Ward,PZ_UserType,PZ_GridStatus,PZ_Country,PZ_WardStatus,PZ_NHS_Code,PZ_NHS_Region,PZ_Long,PZ_Lat,PZ_OSRef,PZ_Update
"AB101AA","20070339","39420","80630","00","QA","MH","1","1","179","1","SN9","S00",-2.097472,57.147616,"NJ9420006300","08/07/09 00:00:00"
"AB101AF","19951239","39410","80640","00","QA","MH","1","1","179","1","SN9","S00",-2.099127,57.148513,"NJ9410006400","08/07/09 00:00:00"
"AB101AG","19951239","39420","80630","00","QA","MH","1","1","179","1","SN9","S00",-2.097472,57.147616,"NJ9420006300","08/07/09 00:00:00"
"AB101AH","19951239","39430","80630","00","QA","MH","1","1","179","1","SN9","S00",-2.095819,57.147617,"NJ9430006300","08/07/09 00:00:00"
"AB101AJ","19980739","39410","80630","00","QA","MH","0","1","179","1","SN9","S00",-2.099125,57.147615,"NJ9410006300","08/07/09 00:00:00"
"AB101AL","19951239","39430","80650","00","QA","MH","0","1","179","1","SN9","S00",-2.095824,57.149414,"NJ9430006500","08/07/09 00:00:00"
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