[GRASS-user] Re: How to add new columns of number of nodes and length of line vector ?

SGW00412 at nifty.com SGW00412 at nifty.com
Mon Oct 31 07:26:19 EDT 2011

Dear Richard and all

> Yasuo -
> For length:
> v.to.db map=line_db option=length units=k column=length
> This would put the length of the line into the column, in kilometers. If 
> you want some other unit, check v.to.db --help to choose the right 
> parameter.

Thank you for useful adivece!

I also saw grass 6.4 manual and found it.

Upload line lengths (in meters) of each vector line to attribute table (use v.
category in case of missing categories):
v.to.db map=roads option=length type=line col=linelength units=me

> I don't know how to check the node count - someone else may help there.

....please give me some information about it...

Yasuo shimada ( JWA )
SGW00412 at nifty.com wrote:
> Hi grass users;
> We traced bird migration by marine radar.
> By using graphic analyze of radar monitor capture on PC, we had  many line 
> vectors of bird flight.
> I would like to add new columns of the number of node and lenght of line 
> So;
> v.db.addcol line_db columns="num_node int"
> v.db.addcol line_db columns="length double precision"
> After that, to update and fill two columus, what commands do I use ?
> I think...can I use SQL query with spatilite...is it right ?
> Best
> Yasuo shimada ( Japan Weather Association )

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