[GRASS-user] db.? to change column names

[Moritz Lennert]

On 31/08/18 16:43, Rich Shepard wrote:
> On Fri, 31 Aug 2018, Moritz Lennert wrote:
> 
>> Markus gave you the name of a module, but just to make sure: the column
>> content in your attribute table does not change because you reproject, so
>> your columns lat and lon should still contain lat and lon values.
> 
> Moritz,
> 
>     Yes, this is correct: they do.
> 
>     However, v.out.ascii produced the projected coordinates, not the
> geographic lon/lat; e.g.,
> 
> 10332|2324618.93021014|214826.06781179
> 10335|2330789.44861867|202224.65265656
> 
>     While in the GUI attribute table manager this is seen:
> 10332|-122.7475|45.977544
> 10335|-122.644139|45.466111
> 
> and there are no easting/northing columns.

Normal:

The first (v.out.ascii) is an output of the information on the 
geometries (the points). The second is the attribute table linked to 
those geometries.

> 
>    Here's the script (line breaks set by MUA; entered on one command line):
> 
>     Using lon_lat location:
> v.in.ascii in=wrb-stations.dat out=stations text=doublequote skip=1
> columns='site_nbr varchar(5), site_name varchar(64), lon double precision,
> lat double precision' x=3 y=4 z=0
> 
>     Exit grass, restart and create new location/mapset, then:
> v.proj loc=lon_lat map=PERMANENT in=stations
> v.out.ascii -c in=stations out=stations.dat type=point columns='*' format=point --o
> v.to.db map=stations opt=coor columns='easting,northing'
> 
>     Closed that map in the GUI and re-loaded it; still no easting/northing
> columns only lon/lat.

To get the data into columns, try this:

v.db.addcolumn stations col="easting double precision, northing double 
precision"
v.to.db map=stations opt=coor columns='easting,northing'

Then you should see the easting and northing columns in the attribute 
table. Not need to export and reload.

Moritz