Details Ticket 249


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Serial Number 249
Subject r.rescale: -z flag wanted
Area wish
Queue grass
Requestors neteler@itc.it
Owner alange
Status resolved
Last User Contact Sun Mar 24 15:31:31 2002 (6 yr ago)
Current Priority 30
Final Priority 70
Due No date assigned
Last Action Sun Mar 24 15:31:38 2002 (6 yr ago)
Created Wed May 2 13:51:34 2001 (7 yr ago)

Transaction History Ticket 249


Wed, May 2 2001 13:51:34    Request created by mneteler  
Subject: r.rescale: -z flag wanted

  r.rescale input=asp1 from=0,180 output=test_north to=1,1
  r.rescale does not set cells outside the "from" range to 0 (described in the
help), but to NULL
  (reported by timcera@earthlink.net)

Andreas Lange, 10/2000: This is IMHO not a bug, but a feature. All modules
  should write NULL instead of 0 (zero) for missing values for patching 
  maps or display overlays. 
  But if the problem with r.reclass is solved i can add a "-z" flag that
  switches this behaviour from writing NULL to writing "0" (zero).
  (being worked on by Andreas Lange)
Fri, Nov 9 2001 01:22:24    Taken by alange  
Fri, Nov 9 2001 13:55:44    Mail sent by bernhard  
If the current documentation differs from the help documentation
this is at least a bug in the documentation, isn't it?
Fri, Nov 9 2001 14:57:31    Mail sent by alange  
I'll look into this. 
I think the documentation should be updated when the module is updated. 
r.rescale needs some work IMHO. 

Andreas
Fri, Nov 9 2001 16:37:12    Mail sent by alange  
I have looked into this.

The problem is that r.rescale calls r.reclass.
But r.reclass does not work with a catch-all clause like this:

* = 0

It only works with the _last_ rule like this:

* = NULL

There is a commented code block in reclass.c which describes this.

If i do a reclass (e. g. on geology from spearfish) like this:
1 = 100
2 = 200
3 = 300
* = 9

all cells outside the range 1..3 are NULL. 

The code in reclass.c exceeds my current capacity. 
Perhaps someone else is able to fix r.reclass to work correctly.
Then the -z flag will be trivial to implement. 

Andreas
Fri, Jan 4 2002 18:05:40    Mail sent by mneteler  
Hi Andreas,

is r.reclass changed already? May I ask you to test it
again (r.reclass was changed some time ago).

Thanks,

 Markus
Fri, Jan 4 2002 18:06:34    User changed to neteler@itc.it by mneteler  
Fri, Jan 4 2002 22:54:16    Mail sent by alange  
The described problem still exists.

The catch-all rule:
*=0
does not work. All values not catched with an other reclass rule are still 
reclassed to NULL, irrespectively of the '*'-rule.
I think that this is an inherent problem of the r.reclass parser.

Andreas
Sun, Mar 24 2002 15:31:31    Mail sent by gclements  
The problem was that the range of the reclass map is limited to the categories
which are listed explicitly in the rules. '*' only applied to undefined
categories within that range.

I have committed a fix for this.
Sun, Mar 24 2002 15:31:38    Status changed to resolved by gclements  
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