Hi David,
No problem, I believe all have gone through the same one time. So I will
try to be more explicit. "Merge by value" is a simple and straight
forward way to execute a complex and very useful operation which is, if
I understand correctly, what you need. Few conditions and steps should
be considered though:
1) You will need a polygon geographic layer/file (.CDF or .DBD) that
would be able to aggregate (both graphically and logically) into the
desired graphic results (lets call these new features Districts). This
option is very handy to automatically create boundaries of States
aggregating counties, for instance. Or Countries out of States or
Municipalities. The marvelous thing is that there is no need of redraw
(re-digitize) a single feature, as the program automatically removes the
inner boundaries according to a logic procedure. On top of that, the
user decides which and how attributes fields will be added (merged). As
Maptitude is a fully topological GIS, all possible complex features
would be aloud to be created, such as Districts with "holes" or polygons
with "islands" separated from the "continent". I believe that you
already have that layer available, that would be ZIP code polygons of
USA. The other wonderful characteristic of using this command is that it
won't change anything on the original file, the only modification
required is to create a field that would contain the "ID's" "Codes" or
"Names" of the new Districts, it is your choice, and if I am not
mistaken that could be numbers or character strings. That takes us to
the next step...
2) On the attribute table of the "Seed" or "Origin" geographic file (as
described above), create (using Modify table) a field that would
contains the codes used to perform the aggregation into your districts.
Fill the column accordingly to your needs and you are ready to go.
Please note that there are a lot of ways to fill codes or names on a
dataview column. I believe that selecting the big areas that contains
several smaller polygons of the same type (Name) first would be wise.
One "trick" I frequently use is to create a color map using this column
in order to check out if my new districts would be OK. The only
difference is that you will have a bunch of smaller areas that later on
would be fused or merged by the Merge by value command.
3) Now you would have to call the Merge by value command, indicate the
desired field (the one you have created) and if desired, the way you
want to aggregate the attribute fields of the "Origin" area layer. That
is all. Remember, no modification is made to the original file, so you
can simply erase the result and do it again as many times as needed.
Hoping this would be useful. Cheers,
Reinaldo
------------------------------------------------------------------------
David Brown wrote:
Hi Reinaldo,
First off I would like to thank you for answering posts! But, I am
still new with Maptitude and I was not able to understand your reply.
If you could please expand on your instructions it would be very
helpful, thank you!
~David
--- In [email protected] <mailto:Maptitude%40yahoogroups.com>,
Reinaldo Paul Pérez Machado <rpmgis@...> wrote:
>
> Hi David,
>
> Yes & yes. Create a column on your polygon geographic layer that could
> aggregate the desired resulting layer, i.e. ZIP codes. Then place the
> proper names/codes into that field. Finally use the "Merge by value"
> option to get the desired results.
>
> Good luck!
>
> Reinaldo
>
> ----------------------------------------------------------
>
> David Brown wrote:
> >
> >
> > Is there a way to combine 2 districts into one district?
> > or
> > Is there a way to create one district that is 1 whole county and part
> > zip codes, how would I create one district around the selected county
> > and the selected zip codes? Thanks!
> >
> >
>
