[GRASS-dev] Error reading null row 2725 for <MASK>

[Paulo van Breugel]

On Mon, Sep 1, 2014 at 10:45 AM, Paulo van Breugel <p.vanbreugel at gmail.com>
wrote:

>
> On Thu, Aug 28, 2014 at 7:34 AM, Paulo van Breugel <p.vanbreugel at gmail.com
> > wrote:
>
>>
>>
>>
>> On Wed, Aug 27, 2014 at 8:20 PM, Markus Neteler <neteler at osgeo.org>
>> wrote:
>>
>>> On Wed, Aug 27, 2014 at 3:25 PM, Paulo van Breugel
>>> <p.vanbreugel at gmail.com> wrote:
>>> > I forgot to mention that I am using GRASS 7.1 (rev 61757, had it
>>> before with
>>> > rev 61413, but I think I had a similar problem about a year ago).
>>> >
>>> > On Wed, Aug 27, 2014 at 10:13 AM, Paulo van Breugel <
>>> p.vanbreugel at gmail.com>
>>> > wrote:
>>> >>
>>> >> When running several r.mapcalc in a loop (via R) the function stops
>>> with
>>> >> an error:
>>> >>
>>> >> ERROR: Error reading null row 2725 for <MASK>
>>>
>>> The error comes from read_null_bits() in
>>> lib/raster/get_row.c
>>>
>>> around
>>> http://trac.osgeo.org/grass/browser/grass/trunk/lib/raster/get_row.c#L827
>>>
>>> Maybe some off_t definition is missing?
>>>
>>
>> I don't know what that means; indication of something being wrong with
>> the data, or in the code?
>>
>>
>>>
>>> >> The row number varies. This seems to happen at random, and when I
>>> repeat
>>> >> the same r.mapcalc calculation that stopped with the error before,
>>> things
>>> >> run without problem.
>>>
>>>
>>> Please tell us also
>>> - how many raster cells are involved
>>> - how many files are opened in the loop?
>>>
>>
>>
>> Last time the error occured in the r.mapcalc below:
>>
>>   The command:
>> r.mapcalc --overwrite expression="OUTPUT = if(MESSC==0, 100000* 100.0 *
>> (MESSB-12300000)/(382900000-12300000), if(MESSC<=5000000, 2*MESSC,
>> if(MESSC<=10000000, 2*(10000000-MESSC),100000 * 100.0 * (382900000-
>> MESSB)/(382900000-12300000))))"
>> produced an error (1) during execution:
>>
>> ERROR: Error reading null row 2725 for <MASK>
>>
>>
>> These layers have 6515140 raster cells, with 3366825 total null cells.
>> The command is part of a sequence of commands that is run in a loop, but
>> these are run in sequence so at the time of the error I guess two layers
>> were open. As I mentioned, running the command again and it will normally
>> run without problems with the given input layers, and it may go wrong with
>> other input layers again, without any discernible logic to me.
>>
>>
>>> >> I tried after removing the mask, and this time no problem so it may
>>> have
>>> >> to do something with the MASK? (as these error messages only occur
>>> once in a
>>> >> while, I can't be completely sure it only happens when a MASK is
>>> defined).
>>> >>
>>> >> I ran it through R, using the execGRASS() function of the spgrass6
>>> >> package. I ran the same, but using the system call instead of
>>> execGRASS.
>>> >> Still got the same error messages. I therefore guess this has nothing
>>> to do
>>> >> with R?
>>>
>>> Could you "simulate" the loops in a GRASS script outside of R to see
>>> if it the same?
>>>
>>
>> I'll have to figure out how to do that. Perhaps running the r.mapcalc
>> above several times will do the trick.
>>
>
> I ran the same calculations, but this time as a list of grass commands in
> a text file, which I subsequently ran from the command line
> (./runMyscript.txt). Same error, so this does not seem to be related to R.
>
> Perhaps totally coincidence, but in all cases I remember I encountered
> this problem, I was running r.mapcalc expressions with an 'if' function
>


And a further update: I the same r.mapcalc calculations with and without
MASK defined, and it as far as I can see, this seems to happen only when a
MASK is defined.

>
>
>>> Markus
>>>
>>
>>
>
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