Revision as of 14:43, 25 February 2008 by Timmie (first text input: summaraized threads from ML)
- Is there a simple way to join some attribute data in a comma separated text file to an existing GRASS vector map?The data in the CSV file does not have any coordinates but a primary key field that also exists in the polygon map it needs to be joined to.
- Answer 1:
- use rdbms as data backend (including for the map you want the data to be connected to)
- create view combining map attribute table with new table from csv-file (using key)
- v.db.connect -o map table=NewView
- Answer 2:
- install SQLite (it does not need setup but works out of the box)
- set the DBMI settings with db.connect (see manual page for copy-paste example)
- use v.db.join
- use g.copy or db.copy to easily transform from DBF (or whatever to SQLite).
- Answer 3:
- identify names and types of columns in csv file
- v.db.addcol the relevant columns
- for each line in csv file: v.db.update
- Answer 1:
- Is there a tool which can convert a dBase file into a ASCII or CSV file?
- Is it safe to edit the DBF-table outside of GRASS in another program? For instance in OpenOfficeCalc? Or even as a CSV with Python, IDL, etc.?
- Yes. You can actually create whatever dbf you want, wherever you want as long as it contains a column with the id's of the objects. Then you can connnect your vector map to this dbf with v.db.connect.