[GRASS5] [bug #3188] (grass) v.net.iso: some roads cost, others distance: sorry

GRASS GIS GRASS GIS developer
1

this bug's URL: http://intevation.de/rt/webrt?serial_num=3188
-------------------------------------------------------------------------

v.net.iso afcolumn=cost allows us to use a cost instead of a distance
for segments.

OK, what if on some of my roads I want to use cost, and some I want to
use distance?

Surprise surprise, nope. It's either all cost, all distance, or close
the road with -1.

Forget about DELETE FROM table WHERE cat =
road_I_want_measured_by_distance, v.net.iso will go nuts.

OK, then what are you going to set its value to in the table, -1? 0?
-1 is for closed roads. 0 is for 0 cost roads.

Nope. "The software engineers never considered this possibility."!!!

The solution for now would be: if the row is not found in the table,
then measure distance. Better would be -2: use distance.

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From jidanni@jidanni.org Wed Apr 27 00:57:51 2005

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To: GRASSLIST@baylor.edu
Cc: grass-bugs@intevation.de
Subject: v.net.iso: some roads cost, others distance: sorry
From: Dan Jacobson <jidanni@jidanni.org>
Date: Wed, 27 Apr 2005 05:00:27 +0800
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2

Just for others, so that they don't get wrong impression.
If you need to use costs you can calculate them in the database (use postgres). In this special case something like:
v.to.db option=length
echo "update my set cost = length where costs is null" | db.execute.

Radim

Request Tracker wrote:

this bug's URL: http://intevation.de/rt/webrt?serial_num=3188
-------------------------------------------------------------------------

v.net.iso afcolumn=cost allows us to use a cost instead of a distance
for segments.

OK, what if on some of my roads I want to use cost, and some I want to
use distance?

Surprise surprise, nope. It's either all cost, all distance, or close
the road with -1.

Forget about DELETE FROM table WHERE cat =
road_I_want_measured_by_distance, v.net.iso will go nuts.

OK, then what are you going to set its value to in the table, -1? 0?
-1 is for closed roads. 0 is for 0 cost roads.

Nope. "The software engineers never considered this possibility."!!!

The solution for now would be: if the row is not found in the table,
then measure distance. Better would be -2: use distance.

--- Headers Follow ---

From jidanni@jidanni.org Wed Apr 27 00:57:51 2005

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To: GRASSLIST@baylor.edu
Cc: grass-bugs@intevation.de
Subject: v.net.iso: some roads cost, others distance: sorry
From: Dan Jacobson <jidanni@jidanni.org>
Date: Wed, 27 Apr 2005 05:00:27 +0800
Message-ID: <873btd6yok.fsf@jidanni.org>
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