Networks / Arcs

Malcolm Williamson malcolm at
Fri Oct 21 08:38:18 EDT 1994

> Can anyone point me in the direction of documentation / source code / 
> whatever to do with what I'd call 'network searchs', i.e. the ability 
> (preferably in GRASS) to work with the vectors which constitute a river 
> network, e.g. options such as determining what arcs are upstream of a 
> point on another arc.
> I've been looking at the Programmers Manual concerning vectors - am I 
> right in assuming that the GRASS 'Vect_read_next_line' function will just 
> get the next line as it was put in the data file - it doesn't mean the 
> next arc in a sequence which forms a 'line' ?
> Thanks,
> Steve Culshaw
> NRA North West
> e-mail : nra at (use this for general usage)
> or         sculshaw at (Private - only checked at best 
> biweekly)

First, I must admit to not being familiar with the internal functionality of
the GRASS vector library. However, I think it is a fair guess to say that if
network analysis could be easily done in the GRASS vector format, someone would
have already implemented it! That said, you might be interested in Dana Tomlin's
discussion of a raster implementation of network of analysis in his book
_Geographic Information Systems and Cartographic Modeling_ (Prentice-Hall, 

Cheers, and remember, always use the best tool for the job!
Malcolm D. Williamson - GIS Specialist           E-mail: malcolm at
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-3846 
University of Arkansas              
Fayetteville, AR 72701

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