[GRASS-user] GRASS7.4 TGRASS parse error while mapcalc computatio

Markus Neteler neteler at osgeo.org
Wed Feb 21 05:00:53 PST 2018

On Wed, Feb 21, 2018 at 1:21 PM, Martin Landa <landa.martin at gmail.com> wrote:
> 2018-02-21 12:57 GMT+01:00 Anika Bettge <bettge at mundialis.de>:
>> I use TGRASS to calculate a NDVI.
> btw, recently I was doing something similar in Jena GRASS GIS workshop, see [1].
>> GRASS 7.4.0 (accra32630):~ > t.rast.mapcalc input=b4,b8 output=test1
>> expression="test1 = float(b8 + b4)" basename=test1  --overwrite
>> Starting temporal sampling...
>> Starting mapcalc computation...
>> Ung├╝ltige Karte
>> <S2_0e76f09b_d221_4e88_b7f9_d3S2_0e76f09b_d221_4e88_b7f9_d3b8aad4975d_20180102T140217_B08_10maad4975d_20180102T140217_B04_10m>
>> Parse error
>> FEHLER: parse error
>> ERROR: Error while mapcalc computation
> It seems like your input strds are broken. Try to check all maps
> registered in input b4 and b8 datasets (by t.rast.list).

The full list was printed in Anika's initial email.

> t.rast.mapcalc tries to read non-existing raster map
> S2_0e76f09b_d221_4e88_b7f9_d3S2_0e76f09b_d221_4e88_b7f9_d3b8aad4975d_20180102T140217_B08_10maad4975d_20180102T140217_B04_10m
> in your case.

I think this is a bug.

Vero wrote off-list to me:
    "Sometimes, t.rast.mapcalc has issues with names of maps, it seems
it is pasting together the 2 map names instead of using the
basename... "

I found a related ticket by Leo Hardtke:

> [1] http://training.gismentors.eu/grass-gis-workshop-jena-2018/units/21.html#ndvi-st-computation

This we used for inspiration :)


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