From dlc at halibut.com  Mon Aug 10 00:48:25 2009
From: dlc at halibut.com (David Carmean)
Date: Sun, 9 Aug 2009 21:48:25 -0700
Subject: [Osmlib-user] Detecting closed ways?
Message-ID: <20090809214825.C5303@halibut.com>


Hi,

Have begun trying to use osmexport again, but have not done any ruby for a couple of years.
I need to detect closed ways so that I can export them as polygons rather than 
polyines.

In the rules file, how do I reference the node/way/polygon which being operated on 
so that I can call is_closed on it?

Thanks.


From jochen at remote.org  Mon Aug 10 03:15:12 2009
From: jochen at remote.org (Jochen Topf)
Date: Mon, 10 Aug 2009 09:15:12 +0200
Subject: [Osmlib-user] Detecting closed ways?
In-Reply-To: <20090809214825.C5303@halibut.com>
References: <20090809214825.C5303@halibut.com>
Message-ID: <20090810071512.GD24832@eldorado.topf.org>

On Sun, Aug 09, 2009 at 09:48:25PM -0700, David Carmean wrote:
> Have begun trying to use osmexport again, but have not done any ruby for a couple of years.
> I need to detect closed ways so that I can export them as polygons rather than 
> polyines.
> 
> In the rules file, how do I reference the node/way/polygon which being operated on 
> so that I can call is_closed on it?

Its the implicit object.

Just write:

ways do
    if is_closed?
        :polygons << { ... }
    else
        :lines << { ... }
    end
end

Note that is_closed? only checkes whether the ids of the first and last node
are the same. It doesn't do a geometric check so you might end up with
invalid polygons if the way crosses itself.

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298