[postgis-users] How do you do neighborhood functions?
Craig Miller
craig.miller at spatialminds.com
Tue Apr 13 20:18:31 PDT 2004
I would export the data out of PostGIS and use Fragstats.
--Craig
-----Original Message-----
From: collin [mailto:collin at socrates.Berkeley.EDU]
Sent: Tuesday, April 13, 2004 9:48 AM
To: postgis
Subject: [postgis-users] How do you do neighborhood functions?
Greetings folks,
Question: I would like to find the average height (z2) of all the
points within 10 meters of every point. Any ideas on how to do this?
I have point data from lidar (snippet below). I made point geometry
from the raw data.
time | x2 | y2 |
z2 | int2 | geom2
-------------+-----------------+----------------+---------+------+----------
---------------------------------------
161626.12404 | 10568414.29 | 4247026 | 388.2 | 75 |
SRID=32610;POINT(10568414.29 4247026 388.2)
161626.12407 | 10568414.31 | 4247026 | 388.26 | 74 |
SRID=32610;POINT(10568414.31 4247026 388.26)
161626.1241 | 10568414.33 | 4247026.01 | 388.33 | 75 |
SRID=32610;POINT(10568414.33 4247026.01 388.33)
I tried
UPDATE napatest SET z2avg10 = avg(z2)
WHERE point_inside_circle(geom_point_first, xf, yf, 10);
but this only updated a single row. z2avg10 is a new field I had added.
Is there a standard method for performing neighborhood functions? i.e.
any set of statistics for each and every row about their neighboring points.
thanks in advance,
Collin
GIS informatics researcher, UC Berkeley
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