Dbase (DBF)

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Some ML-Threads

  1. 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.
    1. Answer 1:
      • use rdbms as data backend (including for the map you want the data to be connected to)
      • db.in.ogr
      • create view combining map attribute table with new table from csv-file (using key)
      • v.db.connect -o map table=NewView
    2. 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).
    3. 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
  2. Is there a tool which can convert a dBase file into a ASCII or CSV file?
    1. Answer 1:
    2. Answer 2:
      • ogr2ogr -f CSV output world.shp world
    3. Answer 3:
      • db.out.ogr
    4. Answer 4:
    5. Answer 4:
    6. Answer 5:
      • OO.org Base instead of Calc
  3. 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.?
    1. Answer:
      • 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.