[GRASS-stats] readVECT6 - ogr fails to export some columns

[Markus Metz]

On Fri, Apr 20, 2012 at 4:47 PM, Eric Momsen <eric.momsen at ndsu.edu> wrote:
> Hi,
>
> I've been using GRASS and R for a few months now, and just ran into a snag.
>  We added some new attribute columns to our vector file in GRASS, and now
> when I try to move the data into R the transfer fails.
>
> The original vector map in grass was imported from a shapefile.  I then used
> v.db.addcol and v.rast.stats to add more attributes to the vector map.
>
> I first thought it had to do with null values, so I tried adding a column
> filled with a constant value.  This didn't help.
>
> I tried to reproduce the error in SPEARFISH, columns added with v.rast.stats
> were fine, but v.db.addcol wouldn't execute.
>
>
> I don't know why the installation let me add columns in one location and not
> another, maybe this is the root cause or another issue all together?
>
> v.db.addcolumn --verbose map=landuse at PERMANENT layer=1 columns=test
>
> Adding column <test> to the table
> DBMI-DBF driver error:
> SQL parser error (syntax error, unexpected $end processing
> '') in statement:
> ALTER TABLE landuse ADD COLUMN test

I think the column type is missing. Try e.g.
v.db.addcolumn --verbose map=landuse at PERMANENT layer=1 columns='test
double precision'

> Unable to execute statement.
> ERROR: Error while executing: 'ALTER TABLE landuse ADD COLUMN test'
> ERROR: Unable to add column <test>.
>
>
> Any ideas for what I'm missing, or a workaround to get the data to R?  (I
> was supposed to get an R data file ready today for others to work with that
> aren't used to GRASS...I had previously done the GRASS->R transfer via a
> script a number of times, and didn't expect any problems!)
>
> Here are the R messages:
>
>> source("/home/emomsen/Documents/loaddata.R")
>
> first command in file:
> field2007<-readVECT6("ACSC_2007_Field_Boundary")
>
> Loading required package: rgdal
> Geospatial Data Abstraction Library extensions to R successfully loaded
> Loaded GDAL runtime: GDAL 1.9.0, released 2011/12/29
> Path to GDAL shared files: /usr/local/share/gdal
> Loaded PROJ.4 runtime: Rel. 4.8.0, 6 March 2012, [PJ_VERSION: 480]
> Path to PROJ.4 shared files: (autodetected)
> Available OGR Drivers:
> Warning 1: Field COUNTY of width 1000 truncated to 255.
> ....snip... these are OK
> ERROR 6: Failed to add field named 'HARVEST_DAY'
> ERROR 6: Failed to add field named 'NDVI_04_B_DAY'
> ....snip...These were added with v.db.addcol
> ERROR 6: Failed to add field named 'NDVI_04_B_mean'

The column name is probably too long for the OGR dbf driver, the max
length is 10 I think. That is, NDVI_04_B_DAY becomes truncated to
NDVI_04_B_ and NDVI_04_B_mean also becomes truncated to NDVI_04_B_,
resulting in duplicate column names. You could try a shorter column
prefix with v.rast.stats.

Markus M

> ...snip,... there are about 100 of these, extended statistics for 10
> rasters.
>
>
> The import does finish, all of the "original" columns for the shapefile are
> imported to R.  v.db.select shows most of the attribute columns together
> (the last ones are lost from the line length), and querying the map gives
> all the attributes.
>
> Thanks for any help!
>
> Eric
>
>> sessionInfo()
> R version 2.14.1 (2011-12-22)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
>  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
>  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
>  [7] LC_PAPER=C                 LC_NAME=C
>  [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] rgdal_0.7-8     spgrass6_0.7-10 XML_3.9-4       sp_0.9-98
>
> loaded via a namespace (and not attached):
> [1] grid_2.14.1    lattice_0.20-0
>
>
> g.gisenv -n
>
> LANG=en_US.UTF-8
> GRASS_ADDON_PATH=/home/emomsen/v.krige
> GISDBASE=/home/shared/research/GRASSDATA
> LOCATION_NAME=transferField
> ADDON_PATH=/home/emomsen/v.krige
> GUI=wxpython
> MAPSET=PERMANENT
>
>
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