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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | GISList: Table woes in AML land |
| Date: |
07/31/2003 01:50:01 PM |
| From: |
Analisa Gunnell |
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Greetings fellow listers,=20
I am running an AML to determine areas of high watershed protection priorit=
y using a 6th field HUC coverage and numerous other data sets. The AML bas=
ically begins by doing an Intersect on the coverages, and then a relate. O=
nce the relate is set, I am working on doing basic math on the table to ide=
ntify percentage of intersected areas (for polygon coverages), mi/mi2 (for =
line coverages), and then frequency (for point coverages). The problem is =
this, for some reason the aml will not calculate my mi/mi2 for line coverag=
es. This is the code that I am first tried using:
relate add int_rel %p%.frq info huc_num2 huc_num2 linear rw
sel shed6.pat
&if %fet% =3D poly &then
ca %p% =3D int_rel//area / area * 100
--->&if %fet% =3D line &then
ca %p% =3D int_rel//length * 0.0006213711922 / area * 0.00000038610=
03
&if %fet% =3D point &then
ca %p% =3D int_rel//frequency
=20
This worked great for polygons and points but gave me 0 values for lines.=
=20=20
I then tried to break up the equation into two parts, since the table would=
not recognize parenthesis around the second portion of the equation (/ are=
a * 0.0000003861003) reading it as a "(area does not exist". Here is my um=
pteenth attempt:
relate add int_rel %p%.frq info huc_num2 huc_num2 linear rw
sel shed6.pat
&if %fet% =3D poly &then
ca %p% =3D int_rel//area / area * 100
--->&if %fet% =3D line &then
ca %p% =3D int_rel//length * 0.0006213711922 <-- converts meters to=
miles
&if %fet% =3D line &then
ca %p% =3D %p% / area * 0.0000003861003 <-- divides the above equat=
ion by square miles (mi/mi2 hopefully)
&if %fet% =3D point &then
ca %p% =3D int_rel//frequency
Which still gives me null values for my intersected line items. Anyway, it=
is probably obvious that I am not aml savvy, but if any of you are and can=
see my algebraic table oversight, your insight would be invaluably useful.=
Thanks!
Analisa Noel Gunnell=20
GIS Technician=20
Ecotrust=20
721 NW Ninth Avenue, Suite 200=20
Portland, Oregon=20
97209=20
503.467.0750
analisa@ecotrust.org=20
www.ecotrust.org=20
www.inforain.org
CONSERVATION ECONOMY
ECOLOGY-ECONOMY-EQUITY
=A0
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