#3857: r.mapcalc unable to rename null and cell files
----------------------+-------------------------
Reporter: Hygsson | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 7.6.2
Component: Raster | Version: unspecified
Resolution: | Keywords: r.mapcalc
CPU: x86-64 | Platform: MSWindows 7
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Comment (by wenzeslaus):
Overwriting map you are reading from is not allowed according to the
documentation:
//A map cannot be used both as an input and as an output as in this
invalid expression `oldmap = oldmap + 1`, instead a subsequent rename
using `g.rename` is needed when the same name is desired: //
{{{
r.mapcalc "newmap = oldmap + 1"
g.rename raster=newmap,oldmap
}}}
https://grass.osgeo.org/grass76/manuals/r.mapcalc.html#using-the-same-map-
for-input-and-output-results
It may work in some cases, but it is not guaranteed. Maybe a check of the
inputs and outputs and an error message on Windows and a warning on other
platforms would be backward-compatible solution. Would you mind opening a
new ticket? On the other hand, having this feature (`a = a + 1`) seems
reasonable (but supporting it is more complex).
--
Ticket URL: <https://trac.osgeo.org/grass/ticket/3857#comment:1>
GRASS GIS <https://grass.osgeo.org>
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