TGIS: fix semantic label

[metzm]

Do not treat a semantic label as shortcut or band identifier if it contains text. This PR is needed to support semantic labels such as red, green, blue, mask.

[landam]

@metzm Can you provide example of usage?

[metzm]

Test case, adapted from a test for t.rast.mapcalc:

g.region s=0 n=10 w=0 e=10 res=1 -p

# Generate data
r.mapcalc expr="prec_1 = rand(0, 550)" -s
r.mapcalc expr="prec_2 = rand(0, 450)" -s
r.mapcalc expr="prec_3 = rand(0, 320)" -s
r.mapcalc expr="prec_4 = rand(0, 510)" -s
r.mapcalc expr="prec_5 = rand(0, 300)" -s
r.mapcalc expr="prec_6 = rand(0, 650)" -s

t.create type=strds temporaltype=absolute output=precip_abs1 title="A test" descr="A test"

echo "prec_1|2001-01-01|2001-01-10|prec1" >testlist
echo "prec_2|2001-01-01|2001-01-10|prec2" >>testlist
echo "prec_3|2001-01-01|2001-01-10|prec3" >>testlist
echo "prec_4|2001-02-01|2001-02-10|prec1" >>testlist
echo "prec_5|2001-02-01|2001-02-10|prec2" >>testlist
echo "prec_6|2001-02-01|2001-02-10|prec3" >>testlist

t.register type=raster input=precip_abs1 file=testlist

t.info in=precip_abs1
t.rast.list in=precip_abs1 columns=name,semantic_label

t.rast.mapcalc inputs=precip_abs1.prec1,precip_abs1.prec2 expression="precip_abs1.prec1 / precip_abs1.prec2" output=precip_mapcalc basename=precip_mapcalc

[neteler]

(I initially had an issue with the creation of testlist due to a double run of the test).

Tested successfully.

[metzm]

I would prefer to remove all modifications to the provided semantic label in _update_where_statement_by_semantic_label(), but this would be another PR.

[wenzeslaus]

I would prefer to remove all modifications to the provided semantic label in _update_where_statement_by_semantic_label(), but this would be another PR.

Just from a quick look here, I agree. Perhaps the whole nested label syntax (and aliases?) can be dropped and replaced by simple look up.

[wenzeslaus]

FYI, none of the t.rast.mapcalc tests actually runs automatically. Maybe all is needed is moving the files to a testsuite directory (there is none in the t.rast.mapcalc directory now). Bash scripts should just run at least in the Ubuntu CI and obviously locally on a right machine and the test above seems self-contained, so hopefully no trouble there either.

[metzm]

I prefer to just delete all modifications to the provided semantic label, requiring that the provided semantic label exists. The reason for these modifications to the provided semantic label is unknown: no code comments.

Alternatively, if the provided semantic label does not exist in the strds, try to modify it, but check if the modified label exists. That would be some overhead, querying the TGIS db is rather slow.