[GRASSLIST:2649] Re: eliminating stream fragments

[Radim Blazek]

On Monday 16 February 2004 19:09, Christopher Fonnesbeck wrote:
> On Feb 11, 2004, at 5:02 AM, Radim Blazek wrote:
> >> There have been posts recently about how to remove polygon islands; on
> >> a related note, I am wondering what is the best method for removing
> >> line fragments from a stream coverage. That is, bits of the stream
> >> coverage that are isolated from the main network due to the
> >> accumulation threshold value specified in the generation of the stream
> >> network. It doesnt look like v.clean does this, but please correct me
> >> if I'm wrong.
> >
> > v.clean tool=rmdangle removes 'dangles', i.e. lines with one free end.
> > This tool is intended for cleaning of boundaries. If you use it for
> > river network, it removes also short lines connected to network.
> > The tool you need should be added to v.clean tools.
> >
> > I thing, that v.net.alloc (http://mpa.itc.it/radim/g51/v.net.alloc.png)
> > can help you. Place just one point at any node of the network
> > and use its category in ccats option, v.net.alloc will allocate
> > whole connected network and isolated lines will be left without
> > category.
>
> How does one "place points" with v.net.alloc? I have browsed the
> documentation, and assume it has something to do with the ccats
> argument, but am not clear what this argument does, based on the
> examples given in the html docs.

Sorry, not at any node but at one node (one point). You have to do that 
by hand in v.digit.

Radim