[GRASS-user] r.cost vs. costallocation (arcgis)

[António M . Rodrigues]

Following my last two messages, to which I got no reply, I'll try to explain my situation a bit better...

For over 10 years, I used ESRI tools (AV Spatial Analyst, ArcInfo costdistance, ArcGIS costallocation) 
to calculate accessibility and allocation surfaces, based on the cost surfaces methodology.

Recently, when starting a new project, I decided to demonstrate that I could do everything related to 
spatial analysis and statistics using only opensource software (R, GRASS and QGIS). Everything is 
actually going quite well, except for the problem I will again describe.

Cost distance and costallocation (arcinfo and arcgis) output two surfaces: an accessibility and an 
allocation surface.

For verious reasons, I need both.

In GRASS, I had a look at r.cost, r.walk r.watershed and r.drain, trying to find a toll which could create 
an allocation grid based on a cost surface. From what I could see, none of these tools will do.

I find it hard to believe that:
	1. No one have had this problem before using GRASS,
	2. there is no solution using GRASS.

If someone, anyone, could point me in "any" direction, it would be greatly appreciated. Even 
something like: "dude, just give up, and go back to arcgis"...

If the solution involves programming a new tool, probably based on r.cost, is there some tutorials 
online dealing with programming in GRASS?

Thank you.
António