[R-sig-Geo] Problem with readRAST6

[Roger Bivand]

On Fri, 29 Jan 2010, Rainer M Krug wrote:

> On Fri, Jan 29, 2010 at 2:32 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>
>> On Fri, 29 Jan 2010, Rainer M Krug wrote:
>>
>>  Hi
>>>
>>> I have a question concerning readRAST6 and the plugin. When I use the
>>> default (plugin=NULL), I get the error below,
>>>
>>
>> Well, this does happen. I never knowingly use the plugins for raster or
>> vector any more, because I have multiple GDAL and GRASS installations, and
>> the cross-dependencies take more time to manage than any accruing benefit.
>> Use plugin=TRUE to avoid the sanity check.
>>
>> If you would like to find the cause, please run debug(readRAST6) first,
>> then run the command, and print out the values of gg (returned by gmeta6()),
>> and fninfo (returned by GDALinfo). The values of gg$n and fninfo[5] are
>> found to differ, but gg$w and fninfo[4] not. It could be that fninfo[5] is
>> set wrongly; in GDALinfo, it is:
>>
>>        ysign <- sign(gt[6])
>>        offset.y <- ifelse(ysign < 0, gt[4] + ysign * d[1] *
>>            abs(cellsize[2]), gt[4] + abs(cellsize[2]))
>>
>> where gt is the vector of values returned by RGDAL_GetGeoTransform from the
>> file-specific driver, and d[1] is the number of rows.
>>
>> If you in addition say debug(GDALinfo), and print the values of gt, we
>> could see whether the values seem sane for this driver. They "must" be
>> anyway for reading with plugin=TRUE to work, because they set up the
>> GridTopology for the object read in; checking with gdalinfo of the same
>> raster would also be helpful.
>>
>> Short answer, use plugin=TRUE if you want to use it.
>>
>
> Thanks Roger - I'll probably do that.
>
>
> But what are the advantages / disadvantages of using the plugin or not?


Because the data are read directly from the GRASS GISDBASE file into R 
memory without the writing and reading of an intermediary GTiff/shapefile, 
the plugin may be faster. From earlier discussions on the grass-stats 
list, this is the usual justification.

Roger

>
> Rainer
>
>
>> Hope this helps,
>>
>> Roger
>>
>>
>>
>>>  x <- readRAST6("MASK")
>>>>
>>> raster map/current region mismatch detected in components:
>>>          cols            rows origin.northing  origin.easting
>>>          TRUE            TRUE           FALSE            TRUE
>>> set plugin=TRUE to override; continuing with plugin=FALSE
>>>
>>> I am absolutely sure, that the raster map:
>>>
>>>
>>>  execGRASS("r.info", parameters=list(map="MASK"))
>>>>
>>>
>>> +----------------------------------------------------------------------------+
>>> | Layer:    MASK                           Date: Fri Jan 29 13:19:03 2010
>>> |
>>> | Mapset:   HLsim_Rtmpe2v0qc               Login of Creator: rkrug
>>>  |
>>> | Location: grass
>>> |
>>> | DataBase: /home/rkrug/Documents/Projects/HakeaLandscape/trunc/
>>>  |
>>> | Title:    Reclass of region in HLsim_Rtmpe2v0qc ( MASK )
>>>  |
>>> | Timestamp: none
>>> |
>>>
>>> |----------------------------------------------------------------------------|
>>> |
>>> |
>>> |   Type of Map:  reclass              Number of Categories: 1
>>>  |
>>> |   Data Type:    CELL
>>>  |
>>> |   Rows:         520
>>> |
>>> |   Columns:      192
>>> |
>>> |   Total Cells:  99840
>>> |
>>> |        Projection: UTM (zone -34)
>>> |
>>> |            N:    6247000    S:    6195000   Res:   100
>>>  |
>>> |            E:     270200    W:     251000   Res:   100
>>>  |
>>> |   Range of data:    min = 1  max = 1
>>>  |
>>> |
>>> |
>>> |   Data Source:
>>>  |
>>> |    Reclassified map based on:
>>> |
>>> |      Map [region] in mapset [HLsim_Rtmpe2v0qc]
>>>  |
>>> |
>>> |
>>> |   Data Description:
>>> |
>>> |    generated by r.reclass
>>> |
>>> |
>>> |
>>> |
>>> |
>>>
>>> |----------------------------------------------------------------------------|
>>> |   Reclassification of [region] in mapset [HLsim_Rtmpe2v0qc]
>>> |
>>> |
>>> |
>>> |         Category        Original categories
>>> |
>>> |
>>> |
>>> |          1              1
>>> |
>>>
>>> +----------------------------------------------------------------------------+
>>>
>>>  execGRASS("g.region", flags="p")
>>>>
>>> projection: 1 (UTM)
>>> zone:       -34
>>> datum:      wgs84
>>> ellipsoid:  wgs84
>>> north:      6247000
>>> south:      6195000
>>> west:       251000
>>> east:       270200
>>> nsres:      100
>>>
>>> gdal info:
>>>
>>>  library(rgdal)
>>>>
>>> Loading required package: sp
>>> Geospatial Data Abstraction Library extensions to R successfully loaded
>>> Loaded GDAL runtime: GDAL 1.6.3, released 2009/11/19
>>> Path to GDAL shared files: /usr/share/gdal16
>>> Loaded PROJ.4 runtime: Rel. 4.7.1, 23 September 2009
>>> Path to PROJ.4 shared files: (autodetected)
>>>
>>>  sessionInfo()
>>>>
>>> R version 2.10.1 (2009-12-14)
>>> i486-pc-linux-gnu
>>>
>>> locale:
>>> [1] LC_CTYPE=en_ZA.UTF-8       LC_NUMERIC=C
>>> [3] LC_TIME=en_ZA.UTF-8        LC_COLLATE=en_ZA.UTF-8
>>> [5] LC_MONETARY=C              LC_MESSAGES=en_ZA.UTF-8
>>> [7] LC_PAPER=en_ZA.UTF-8       LC_NAME=C
>>> [9] LC_ADDRESS=C               LC_TELEPHONE=C
>>> [11] LC_MEASUREMENT=en_ZA.UTF-8 LC_IDENTIFICATION=C
>>>
>>> attached base packages:
>>> [1] stats     graphics  grDevices utils     datasets  methods   base
>>>
>>> other attached packages:
>>> [1] multicore_0.1-3 RSQLite_0.8-0   DBI_0.2-5       spgrass6_0.6-12
>>> [5] XML_2.6-0       maptools_0.7-29 lattice_0.18-3  foreign_0.8-38
>>> [9] simecol_0.6-9   deSolve_1.6     rgdal_0.6-24    sp_0.9-52
>>>
>>> loaded via a namespace (and not attached):
>>> [1] grid_2.10.1  tools_2.10.1
>>>
>>>>
>>>>
>>> Cheers,
>>>
>>> Rainer
>>>
>>>
>>>
>> --
>> Roger Bivand
>> Economic Geography Section, Department of Economics, Norwegian School of
>> Economics and Business Administration, Helleveien 30, N-5045 Bergen,
>> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
>> e-mail: Roger.Bivand at nhh.no
>>
>>
>
>
>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no