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

GRASS GRASS user
1

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 vector,

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 )

2

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.

http://grass.osgeo.org/gdp/html_grass64/v.to.db.html
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...

Best
Yasuo shimada ( JWA )
---
SGW00412@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

vector,

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 )