Indeed, v.extract using the layer option did the job! Thank you Moritz! Probably, I can then use v.category option="chlayer" to change the layer Nr. 3 to Nr. 1!?
On Tue, Aug 9, 2016 at 2:23 PM, Moritz Lennert <mlenn...@club.worldonline.be > wrote: > On 09/08/16 13:48, Johannes Radinger wrote: > >> Hi, >> >> I'd like to create from an existing GRASS vector map that has 3 layers >> (with three attribute tables) a new vector map that has only one >> layer and its associated attribute table (here the information related >> to layer 3). >> >> What I am doing so far (in python): >> >> # First copy the map to a new one and copy table (that of layer 3) >> # that I want to re-connect to new map >> grass.run_command("g.copy", >> overwrite=True, >> vector="oldmap,newmap") >> grass.run_command("db.copy", >> overwrite=True, >> from_table="table_layer3", >> to_table="table_layer3_copy") >> >> # Second delete all tables of the newmap >> for i in [1,2,3]: >> grass.run_command("v.db.droptable", >> flags="f", >> map="newmap", >> layer=i) >> >> # Third reconnect a table to the newmap >> grass.run_command("v.db.connect", >> overwrite=True, >> map="newmap", >> table="table_layer3_copy") >> >> When I check in the attribute table manager, there is only one layer >> listed (layer 1). >> Similarly, v.db.connect reports: >> v.db.connect -p map=newmap >> Vector map <newmap> is connected by layer <1/table_layer3_copy> table >> <table_layer3_copy> in database [...] >> >> However, in d.vect I can still select from all three layers that were in >> the old map (-1,1,2,3), >> and all of them can be displayed (with -1 specified)? >> So does may newmap have three layers or only one? >> > > 3. Layers are defined by category values, not by attribute tables. > > >> How can I make the third layer the default layer 1 and remove all other >> layers? >> Or is there a way to copy a vector map with just a single layer and its >> associated table specified as default? >> > > Try v.extract instead of g.copy. > > Moritz >
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