You might use query SQL to select the set polygons you are targeting and then use the
combine option to amalgamate the selected ones. The trick part is how to set your
query and combine the features in a repeated procedure.
See this simple sequence:
- Create one unique and sequential filed
- Populated it with ID (rowid)
- Select from table1, table2 where table1.obj intersects table2.obj and
table1.field_A=table2.field_A
Based on this general procedure you can complicate this quite nicely. It will depend
on how you want to organize the sequence of events. I would first create a new field
on your table to be used as a tag field, do a first selection by intersect and by
attribute. This will result in a set of polygons that are adjacent to the reference
you have chosen. Update the tag field on this selected set. This will tell you what
polygons are adjacent to one another. After you run it for your entire database, you
can prepare another set of procedures to select and combine but now based on the tag
field, say select from base table tag=1, and do the combine based on some attribute
criteria.
The idea is to do this process in two steps: one to tag the adjacent groups and the
second to actually combine them. This is better because the combine process erases
records and replaces the erased ones by one polygon and you don't want to mess the
selection index because some will be erased.
You can create a txt template of this process and replicate it to batch process or you
can write a MB routine that does the same.
Hope this helps.
Dyan C. Catamaran
GIS/RS Coordinator
---------------------------------
Phero Tech Inc.
www.pherotech.com
[EMAIL PROTECTED]
P:604-940-9944
F:604-940-9433
>>> "Fast, Tim" <[EMAIL PROTECTED]> Tuesday, May 01, 2001 >>>
Folks,
Is there a way in MapInfo or MapBasic to run a Combine based on an attribute
in the browser? I have several tables of regions in which I need to combine
those polygons that are adjacent to one another and share a value based on a
column in the browser. For example I have a column called ID populated with
a smallint. I want to combine all polygons that share the same ID number and
ideally also those that are adjacent.
Thanks,
Tim Fast
Pioneer Hi-Bred International, Inc.
[EMAIL PROTECTED]
_______________________________________________________________________
List hosting provided by Directions Magazine | www.directionsmag.com |
To unsubscribe, send e-mail to [EMAIL PROTECTED] and
put "unsubscribe MapInfo-L" in the message body.
_______________________________________________________________________
List hosting provided by Directions Magazine | www.directionsmag.com |
To unsubscribe, send e-mail to [EMAIL PROTECTED] and
put "unsubscribe MapInfo-L" in the message body.
