On Jul 14, 2008, at 3:54 AM, <[EMAIL PROTECTED]> wrote:
Date: Mon, 14 Jul 2008 12:17:54 +0200
From: "G. Allegri" <[EMAIL PROTECTED]>
Subject: Re: [GRASS-user] mapcalc and cell coordinates
To: "Paul Kelly" <[EMAIL PROTECTED]>
Cc: grassuser <grass-user@lists.osgeo.org>
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1
Yer, but as mapcalc has some built-in functions like x() and y() to
retrieve the x-y coordinates, I think it could be easy to trasform
them in projected coordinates.
I'm writing a few lines in C to solve it, but I think I'll take a look
to r.mapcalc code to see if it would be possible to add something like
x_coord() and y_coord()...
It would be great if you could do this. It is important to coupling
agent-based and other kinds of modeling to GIS functions in GRASS.
Michael
2008/7/14 Paul Kelly <[EMAIL PROTECTED]>:
On Mon, 14 Jul 2008, G. Allegri wrote:
How can I control mapalgebra "if" statements on the base of the
coordinates values of a cell?
The base problem is to change the values of some specific cells on
the
base of their coordinates.
I suspect this might not be possible with r.mapcalc, because each
variable
in an r.mapcalc expression is effectively an entire map and the
expression
used to generate the output map can't be changed based on the co-
ordinates
of individual cells in the input map. I.e., the same expression
applies to
each and every cell in the output map.
That's my understanding anyway, based on an answer Glynn gave me a
few years
ago:
http://lists.osgeo.org/pipermail/grass-user/2003-January/008182.html
Does that seem relevant to your case?
Paul
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