[GRASS-user] Question regarding grass.mapcalc

Glynn Clements glynn at gclements.plus.com
Fri Sep 24 06:58:54 EDT 2010

Kim Besson wrote:

> I'm doing a Python script to calibrate a raster image. Since I need to do 3
> different calculations I'm using a tempfile (tempL)
> This is the code:
>      tempL = grass.read_command("g.tempfile", pid = "1")
>     grass.mapcalc("$L=$lmin+ (($lmax-$lmin)/($QCALmax-$QCALmin))*
> ($raster_file-$QCALmin)", L=tempL, lmin=lmin, lmax=lmax, QCALmax=QCALmax,
> QCALmin=QCALmin, raster_file=raster_file)
> Where tempL is a temporary, (lmin,lmax) are floats, QCALmax and QCALmin are
> int and raster_file is a raster map used as input.
> And I get this:
> syntax error, unexpected '/', expecting NAME or STRING
> Parse error
> ERROR: An error occurred while running r.mapcalc
> What is happening? I believe it has something to do with tempL. Maybe I'm
> not doing this right. Can anyone help me on this?

g.tempfile returns the full pathname to a temporary file, not a map

There isn't a module to generate temporary map names. A common
approach is to use the name of the script followed by ".tmp".

Glynn Clements <glynn at gclements.plus.com>

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