Tue, Oct 8 2002
05:52:23
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Request created by guest
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Subject: r.mapcalc results contain no data
Platform: WindowsNT/2000/XP
grass obtained from: Mirror of Trento site
grass binary for platform: Downloaded precompiled Binaries
GRASS Version: 5.0.0pre3
Hi,
I'm following the tutorial from "GRASS Seeds" at http://www.geog.le.ac.uk/assist/grass/seeds/.
The data set "leics" is also from there.
When using r.mapcalc to get a new layer from two complementary layers, the result
contains no data, whether interactively or non-interactively.
GRASS:~ >r.mapcalc asp_cost=asp_north+asp_south
EXECUTING asp_cost = ... 100%
CREATING SUPPORT FILES FOR asp_cost
GRASS:~ >r.report asp_cost units=percent
...
...
|-----------------------------------------------------------------------------|
| Category Information | %
|
|#|description | cover|
|-----------------------------------------------------------------------------|
|*|no data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|100.00|
|-----------------------------------------------------------------------------|
...
...
GRASS:~ >r.report asp_north units=percent
...
...
|-----------------------------------------------------------------------------|
| Category Information | %
|
|#|description | cover|
|-----------------------------------------------------------------------------|
|1|0 thru 180 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .| 51.35|
|*|no data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .| 48.65|
|-----------------------------------------------------------------------------|
...
...
GRASS:~ >r.report asp_south units=percent
...
...
|-----------------------------------------------------------------------------|
| Category Information | %
|
| #|description | cover|
|-----------------------------------------------------------------------------|
|10|181 thru 360 . . . . . . . . . . . . . . . . . . . . . . . . . . . | 45.34|
| *|no data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . | 54.66|
|-----------------------------------------------------------------------------|
...
...
In fact, the problem also occurs with grass5 on my redhat 7.3 platform, which
I downloaded binaries just a few days ago from a mirror site.
Forgive my poor English.
Thanks,
Zhao Jianwei
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Tue, Oct 8 2002
06:05:52
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Mail sent by guest
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This does not seem to be a bug and the tutorial probably was not written
for GRASS5 with null data. If the layers are complementary and use nulls,
then the result will be nulls. It is necessary to change the nulls
in the complemenary files to zeroes (e.g. using r.null) to get it right.
I suggest that the tutorial should get info attached to it that it may contain
material which is not valid for GRASS5
Helena |
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Tue, Oct 8 2002
09:47:18
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Mail sent by mneteler
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Unfortunately we have no access to the document (we cannot distribute
it due to copyright limitations). The PROJECT ASSIST people do not
answer...
Markus
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Tue, Oct 8 2002
09:47:20
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Status changed to resolved by mneteler
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