Stephen,
A basic adjacency matrix can be created using a sequence of sql
commands to update columns in a table. However, there is a limit of
250 columns which may not be enough for all the divisions in Wales.
The table would need to contain a logical column for each division.
The following code shows how to update that column:
create a counter variable
dim i as smallint
create an alias variable to refer to the table's columns
dim colref as alias
create an object variable to use in the sql below
dim adjobj as object
set initial value of counter and first ( logical ) column, eg zon1
i = 1
colref = zon+i
Start loop
select region
select * from WelshDivisions where rowid = i into target
assign selected table object to variable object
adjobj = target.obj
Select regions adjacent to variable object but excluding itself
select * from WelshDivisions where rowid <> i and obj intersects
adjobj into adjzons
For selected adjacent regions set logical column to true
Update adjzons Set colref = 1
Update variables
i = i + 1
colref = zon+i
Repeat loop
If you have more than 250 regions then you'll have to use a file
rather than a table to record the adjacency flag.
Ian
- - - - - - - - - - - - - - - - -
Ian Robertson,
Information Services, E & D Dept
Leicester City Council, UK.
Tel +44 (0) 116 252 7230
Fax +44 (0) 116 255 6385
EM: [EMAIL PROTECTED]
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