[GRASS-dev] r.mapcalc: using text labels as file names in equations

[Markus Neteler]

Hi,

I have to do computations on raster map combinations: one map contains the
month of interest as pixel value, a set of 12 monthly maps the related values.

My task is to find pixelwise the average temperature of the, say,
warmest month of
a year which's number is stored in the first map called "warmest_month"
along with a text label:
1 jan_tmean
2 feb_tmean
...

I would then need to use these text labels (alias map names) in a r.mapcalc
function which is already working for numerical labels (see pH values in
the manual, accessible with @mapname).

Suggestion: new "?" operator, to allow for this:

r.mapcalc "snow_zone = if(?warmest_month < 3.0, 1, null() )"

This would not read "warmest_month" (1...12) but "jan_tmean" etc instead
and use the label as map name to the numerical extract values from there.

Would it be possible to extend r.mapcalc in this direction?

Markus