[GRASS-user] r.mapcalc appears to have changed behavior

[Michael Barton]

It looks like for the 2nd calculation, your computational region is set to extents of 0W - 1E, 0S - 1N, with a resolution of 1.

So r.mapcalc is only operating on a single 1x1 cell that is outside the area of your raster map.

Michael
____________________
C. Michael Barton
Director, Center for Social Dynamics & Complexity 
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University

voice: 	480-965-6262 (SHESC), 480-727-9746 (CSDC)
fax:          480-965-7671 (SHESC),  480-727-0709 (CSDC)
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu











On Sep 27, 2011, at 11:50 PM, <grass-user-request at lists.osgeo.org> <grass-user-request at lists.osgeo.org> wrote:

> Date: Mon, 26 Sep 2011 23:19:11 -0400
> From: Jim Mochel <jim.mochel.hivol at gmail.com>
> Subject: [GRASS-user] r.mapcalc appears to have changed behavior
> To: grass-user at lists.osgeo.org
> Message-ID:
>        <CAE=Y9-Q7tFZ=cJ4TC6nceYA5B=R9E7RRwZbVfF_fYbMNTEpC6A at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> I had made a number of scripts that worked fine in the 6.4.0 build 6 but
> appear to have problems with the same code in later revisions:
> 
> The method used to take about 6-8 secs and produce about what you would
> expect on the screen. Now the same calculation takes 0 seconds the file is
> radically changed. See the before and after below.
> 
> Any help would be greatly appreciated.
> Thanks
> Jim Mochel
> 
> r.mapcalc na_dem_sub_20 = na_dem_input - 20
> 
> 
> +----------------------------------------------------------------------------+
> | Layer:    na_dem                         Date: Sat Sep 24 17:37:59 2011
> |
> | Mapset:   PERMANENT                      Login of Creator: jmochel
>  |
> | Location: wgs84
> |
> | DataBase: /home/jmochel/grassdata
> |
> | Title:     ( na_dem )
> |
> | Timestamp: none
> |
> |----------------------------------------------------------------------------|
> |
> |
> |   Type of Map:  raster               Number of Categories: 65535
>  |
> |   Data Type:    CELL
>  |
> |   Rows:         8384
>  |
> |   Columns:      9102
>  |
> |   Total Cells:  76311168
>  |
> |        Projection: x,y
>  |
> |            N:    4384500    S:   -3999500   Res:  1000
>  |
> |            E:    4639500    W:   -4462500   Res:  1000
>  |
> |   Range of data:    min = 0  max = 65535
>  |
> |
> |
> |   Data Description:
> |
> |    generated by r.in.gdal
> |
> |
> |
> |   Comments:
> |
> |    r.in.gdal input="/home/jmochel/gis/raw-data/hydo1k/na_dem.bil" outpu\
>  |
> |    t="na_dem"
> |
> |
> |
> +----------------------------------------------------------------------------+
> 
> 
> r.info map=na_dem_sub_20
> 
> +----------------------------------------------------------------------------+
> | Layer:    na_dem_sub_20                  Date: Mon Sep 26 23:06:03 2011
> |
> | Mapset:   PERMANENT                      Login of Creator: jmochel
>  |
> | Location: wgs84
> |
> | DataBase: /home/jmochel/grassdata
> |
> | Title:     ( na_dem_sub_20 )
>  |
> | Timestamp: none
> |
> |----------------------------------------------------------------------------|
> |
> |
> |   Type of Map:  raster               Number of Categories: 610
>  |
> |   Data Type:    CELL
>  |
> |   Rows:         1
> |
> |   Columns:      1
> |
> |   Total Cells:  1
> |
> |        Projection: x,y
>  |
> |            N:          1    S:          0   Res:     1
>  |
> |            E:          1    W:          0   Res:     1
>  |
> |   Range of data:    min = 610  max = 610
>  |
> |
> |
> |   Data Description:
> |
> |    generated by r.mapcalc
> |
> |
> |
> |   Comments:
> |
> |    na_dem_input at PERMANENT - 20
>  |
> |
> |
> +----------------------------------------------------------------------------+