Thanks very much to four of you (C. Perry, M. Roundill, J. Paris, R. Saraf)
who told me about using ObjectGeography and/or the MBR (minimum bounding
rectangle) function to find the min. and max. coordinates of a polygon. This
is simple to do, and two examples should make it clear:
select ObjectGeography(obj,1) "Min_X"
select ObjectGeography(MBR(obj),1) "min_x"
The use of the MBR function in the second example is actually not necessary.
In my case I wanted to find the mean width and height of a set of buffers
built around all of the polygons in one of my tables--the idea was that this
would help me contrast the search distance of these buffers with the search
distance of a set of circles, simply centred around the centroids of the
original polygons. I found I could very rapidly generate the tables I needed
to do this in one step, using the following SQL code in the MapBasic window:
select
ObjectGeography(buffer(obj,10,125,"m"),3)-ObjectGeography(buffer(obj,10,125,
"m"),1) "width" from my_table into width_buff
select
ObjectGeography(buffer(obj,10,125,"m"),4)-ObjectGeography(buffer(obj,10,125,
"m"),2) "height" from my_table into height_buff
Thanks again for the help!
Ian
--------------------
Ian Robertson
Dept. of Anthropology
Arizona State University
Tempe, AZ, 85287-2402
[EMAIL PROTECTED]
-----Original Message-----
I am interested in characterizing central tendancies of the width (E-W) and
height (N-S) of a large number of polygons in a MapInfo table. Is there any
way to generate the minimun and maximum coordinates associated with a
polygon? Thanks much for any help.
Ian Robertson
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