Wed, Aug 16 2006
11:38:23
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Request created by mneteler
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Subject: r.neighbors: add null pass-through support
transferred here from #2398 due to spam bombing
Sun, May 9 2004 14:14:53 Request created by guest
Subject: r.neighbors: add null pass-through support
Platform: GNU/Linux/i386
grass obtained from: Mirror of Trento site
grass binary for platform: Compiled from Sources
GRASS Version: CVS April 2004
r.neighbors should have an option so output maps only contain data where data
exists in the original map.
Currently output maps 'grow' to the search distance, i.e.
output_val=mean(nonNULL(cell_values))
Maybe for completeness/correctness it should have an option to return a value
of null when there is ANY null data as part of the calculation, shrinking the
map at the region bounds and around any null cells, as mathematically the
neighborhood
analysis is only 100% valid in these areas. (-s strict?)
see 'r.series -n'
thanks,
Hamish
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Wed, Aug 16 2006
11:38:48
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Comments added by mneteler
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Date Mon, 10 May 2004 10:37:55 +1200
From Hamish <hamish_nospam yahoo.com>
> ---- Subject: r.neighbors: add null pass-through support
...
> r.neighbors should have an option so output maps only contain data
> where data exists in the original map.
>
> Currently output maps 'grow' to the search distance, i.e.
> output_val=mean(nonNULL(cell_values))
I should have mentioned, the reason this is needed is that r.neighbors
doesn't respect a null MASK when writing the output file, perhaps that
is the real bug.
Hamish |
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Wed, Aug 16 2006
11:39:23
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Comments added by mneteler
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From Glynn Clements <glynn.clements@virgin.net>
Date Mon, 10 May 2004 07:56:14 +0100
To Hamish <hamish_nospam@yahoo.com>
Cc grass-bugs@intevation.de, grass5@grass.itc.it
Subject Re: [GRASS5] Re: [bug #2398] r.neighbors: add null pass-through support
Hamish wrote:
> > ---- Subject: r.neighbors: add null pass-through support
> ...
> > r.neighbors should have an option so output maps only contain data
> > where data exists in the original map.
> >
> > Currently output maps 'grow' to the search distance, i.e.
> > output_val=mean(nonNULL(cell_values))
>
>
> I should have mentioned, the reason this is needed is that r.neighbors
> doesn't respect a null MASK when writing the output file, perhaps that
> is the real bug.
The mask only applies to input, not output.
--
Glynn Clements <glynn.clements@virgin.net> |
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Wed, Aug 16 2006
16:18:25
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Wed, 16 Aug 2006 15:18:03 +0100
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Subject |
Re: [GRASS-dev] [bug #5008] (grass) r.neighbors: add null pass-through support
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Request Tracker wrote:
> this bug's URL: http://intevation.de/rt/webrt?serial_num=5008
> -------------------------------------------------------------------------
>
> Subject: r.neighbors: add null pass-through support
> Maybe for completeness/correctness it should have an option to return a value
> of null when there is ANY null data as part of the calculation, shrinking the
> map at the region bounds and around any null cells, as mathematically the
> neighborhood analysis is only 100% valid in these areas. (-s strict?)
Agreed. There should be an option to propagate nulls.
--
Glynn Clements <glynn@gclements.plus.com>
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