[GRASS-user] More on v.net.steiner

GRASS GRASS user
1

All,

I found a brute-force way to identify the unreachable categories; I set up a loop in d.path to connect all categories to all others, with the output pipelined to a text file along with cats.

OK; with the offending categories removed from the points, I then ran v.net.steiner again.

In Grass-6.3 on Mac OSX, it crashes after the cost initialisation step (Init costs from node ###) with a bus error. However, it works okay in Grass-6.4 on Linux.

Richard Chirgwin

2

On Wed, Sep 9, 2009 at 7:14 AM, Richard
Chirgwin<rchirgwin@ozemail.com.au> wrote:

All,

I found a brute-force way to identify the unreachable categories; I set up a
loop in d.path to connect all categories to all others, with the output
pipelined to a text file along with cats.

Wouldn't v.net do the job?

http://grass.osgeo.org/grass64/manuals/html64_user/v.net.html
-> Example
    "... create lines map connecting points to network (on layer 2)"

Markus

3

Markus Neteler wrote:

On Wed, Sep 9, 2009 at 7:14 AM, Richard
Chirgwin<rchirgwin@ozemail.com.au> wrote:
  

All,

I found a brute-force way to identify the unreachable categories; I set up a
loop in d.path to connect all categories to all others, with the output
pipelined to a text file along with cats.
    
Wouldn't v.net do the job?

http://grass.osgeo.org/grass64/manuals/html64_user/v.net.html
-> Example
    "... create lines map connecting points to network (on layer 2)"

Markus

Markus,

I had already run v.net to create the connection from point to network. Where it fell down was for points that couldn't connect, because v.net.steiner reports the failure to connect using node number rather than category number (so for eg the cat might be 10 but the node 639). My nasty brute-force was to create a text file that clearly put node number and cat number together.

(The network was roads; the points that didn't connect were in the water, which is fair enough I suppose!)

Richard

4

Richard wrote:

I found a brute-force way to identify the unreachable
categories; I set up a loop in d.path to connect all
categories to all others, with the output pipelined to a
text file along with cats.

MN:

> Wouldn't v.net do the job?

RC:

I had already run v.net to create the connection from point
to network. Where it fell down was for points that couldn't
connect, because v.net.steiner reports the failure to
connect using node number rather than category number (so
for eg the cat might be 10 but the node 639). My nasty
brute-force was to create a text file that clearly put node
number and cat number together.

(The network was roads; the points that didn't connect were
in the water, which is fair enough I suppose!)

how about v.net.iso then split away areas with infinite cost.

?

Hamish

5

Hamish wrote:

Richard wrote:
  

I found a brute-force way to identify the unreachable
categories; I set up a loop in d.path to connect all
categories to all others, with the output pipelined to a
text file along with cats.
    

MN: 
  

Wouldn't v.net do the job?
      

RC:
  

I had already run v.net to create the connection from point
to network. Where it fell down was for points that couldn't
connect, because v.net.steiner reports the failure to
connect using node number rather than category number (so
for eg the cat might be 10 but the node 639). My nasty
brute-force was to create a text file that clearly put node
number and cat number together.

(The network was roads; the points that didn't connect were
in the water, which is fair enough I suppose!)
    


how about v.net.iso then split away areas with infinite cost.

?

Hamish

Thanks, I’ll give that a try.

Richard