On 02/12/17 02:03, Peter Tittmann wrote:
Hi,
I have a vector (`POINT`) which has two layers containing relevant
attributes (’strata’ and ’stand’). I would like to concatenate the two
values into a new attribute for Layer 1 (’<STRATA>_<STAND>’). I’ve been
struggling to sort this out for too long and am tapping out. Its
probably blatantly obvious but it has escaped me.
Probably the easiest way if your not very familiar with SQL:
- Create a new column in layer 1 where you can put the info from layer 2
- Fill this column with v.to.db option=query query_layer=2, etc
- Create a second new column to hold the concatenation
- v.db.update to update this new column with the concatenation of the
two others (something like qcol = "STRATA || '_' || STAND")
Otherwise, if there is a common key in both tables, you can just create
a new column and use db.execute to launch a UPDATE TABLE directly,
grabbing the info from the two table and concatenating it directly in
the query.
Moritz
Thank you!
Here are some specifics.
east, north: 651849.842735, 6604949.78485
c34_patch@project_area:
Type: Point
Id: 21622
Layer: 1
Category: 21623
Driver: sqlite
Database: /Users/pete/grassdata/PortGraham/project_area/sqlite/sqlite.db
Table: c34_patch
Key_column: cat
Attributes:
cat: 21623
*strata: 3 — STRATA*
c34_patch@project_area:
Type: Point
Id: 21622
Layer: 2
*Category: 10 — STAND*
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