[GRASSLIST:2233] Re: trend surface analysis - New Problem

[Roger Bivand]

> Hello.
>
> I did as Roger said, and used
>
> base2 <- surf.ls(2, east(G), north (G), isobase)

isobase$isobases.auto not isobase, which is a list that may contain more
than one raster layer.

Roger

>
> but then I get this error msg:
>
>> Error in as.double.default(z) : (list) object cannot be coerced to
>> double
>
> How can fix it?
> I tried as.double(), but get the same msg.
>
> Thanks again
>
> Carlos
> --
> +-------------------------------------------------+
>         Carlos Henrique Grohmann - Guano
>     Geologist - MSc Student at IGc-USP - Brazil
>        Linux User #89721  ICQ: 214752832
> +-------------------------------------------------+
>
>
> Citando Roger Bivand <Roger.Bivand at nhh.no>:
>
>>
>> > Hello all
>> >
>> > I'm trying to do some trend surface analysis with GRASS data in R,
>> but I with some problems:
>> >
>> > 1 - when I get the raster from GRASS, surf.ls() doesn't accept it,
>> since its not in x,y,z format:
>> >
>> >> str(isobase)
>> > List of 1
>> >  $ isobases.auto: num [1:241266] 771 770 769 768 767 ...
>> >>
>> >
>> > So, how can I change this to a format that surf.ls() understands?
>> >
>>
>> isobase$isobases.auto is the z argument. You can generate the x by
>> east() of the object returned by gmeta(), and y by north() of this
>> object. I'm not sure how well surf.ls() scales to this number of
>> points, though.
>>
>> > 2 - I'll try several degrees of surfaces, so I'll use surf.ls(),
>> but
>> what about residuals? can I get them with residuals()?
>> >
>> Yes, residuals() should work. Again, scaling to this number of points
>> is an issue. On the other hand, the residuals and fitted values will
>> drop straight into the GRASS location.
>>
>> Roger
>>
>> > thanks in advance
>> >
>> > Carlos Grohmann
>> >
>> > --
>> > +-------------------------------------------------+
>> >         Carlos Henrique Grohmann - Guano
>> >     Geologist - MSc Student at IGc-USP - Brazil
>> >        Linux User #89721  ICQ: 214752832
>> > +-------------------------------------------------+
>>
>>
>> --
>> Roger Bivand
>> NHH, Breiviksveien 40, N-5045 Bergen, Norway
>>
>>
>>
>>


-- 
Roger Bivand
NHH, Breiviksveien 40, N-5045 Bergen, Norway