[GRASSLIST:2556] Re: eliminating stream fragments

[Radim Blazek]

On Tuesday 10 February 2004 15:52, Christopher Fonnesbeck 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.

Radim