[GRASS-stats] Raster maps from GRASS to R and back to GRASS?

[Dylan Beaudette]

On Fri, Apr 17, 2009 at 6:52 AM, Nikos Alexandris
<nikos.alexandris at felis.uni-freiburg.de> wrote:
> On Tue, 2009-04-14 at 23:36 +0200, Nikos Alexandris wrote:
>> Roger:
>> > Without a reproducible example, we are not going to get anywhere, I'm
>> > afraid. We must have a tarball of the location, and the exact R code being
>> > used.
>>
>> Dylan:
>> > > Can you reproduce this problem with another dataset? How about a subset of the
>> > > data?
>>
>> Sure! After all it's MODIS data I am dealing with (...public domain) and
>> "my" location is not that big. I'll do my best tomorrow or the day after
>> (?). I'll let the list know :-)
>>
>> Cheers, Nikos
>
> Roger and Dylan,
> apologies for not being on-time. I was _forced_ to spend time on other
> things.
>
> I will try to make a clean-check of my attempt one last time and if I
> still can't make it I'll post info + grass-location with the data.
>
> Last time I tried to repeat my test I received the same "random NULL's"
> when using *only* one of the data-sets. I suspect that something might
> be wrong with the data(?!). Not sure though (=I can't find _any_ NULL's
> in the NULL's that are _produced_ when I write the data back from R to
> GRASS).
>
> Kindest regards, Nikos
>

Hi Nikos. I am not sure if this is still a possibility in GRASS, but I
seem to recall that some operations can result in values of 'Nan'...
which isn't properly encoded as NULL. Glynn would know for sure about
this. It could be you have NULL or NULL-like cells that you don't know
about...? r.report, and r.null may be useful in identification of NULL
cells.

Good luck!

Dylan