r.statistics needs to be implemented as a special case in Processing (or removed)

[qgib]

Author Name: Markus Mayr (@scubbx)
Original Redmine Issue: 11967
Affected QGIS version: 2.6.1
Redmine category:processing/grass
Assignee: Victor Olaya

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When using the "r.statistics" GRASS algorithm via the processing toolbox, the output always corresponds to the layer selected as "Base raster layer". There is no calculation performed.
A more specialized algorithm like "r.average" seems to perform the calculation.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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as it is implemented now in Processing, r.statistics cannot work.

The reason is that the result of r.statistic (in native GRASS) is a raster layer that has the same pixel values of the base layer, where the computed statistics are stored into the (GRASS) raster labels.

The computed values can be "extracted" by doing a simple r.mapcalc operation.

So the options are:

1. remove r.statistics from Processing

2. modify GrassAlgorithm.py and add a special case (it has already be done for r.horizon and r.composite) to cope with this special module

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• operating_system was changed from Linux Mint to
• os_version was changed from 17.1 to

[qgib]

Author Name: Giovanni Manghi (@gioman)

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2. modify GrassAlgorithm.py and add a special case (it has already be done for r.horizon and r.composite) to cope with this special module

note:
the map outputted by r.statistics must be processed this way

r.mapcalc "newoutput=@statistics_output"

before outputting (newoutput) with r.out.gdal

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• subject was changed from r.statistics broken? to r.statistics needs to be implemented as a special case in Processing (or removed)

[qgib]

Author Name: Markus Mayr (@scubbx)

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I added the proposed step to the processing code: #2043
For me, this produces valid results now.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• pull_request_patch_supplied was changed from 0 to 1

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• resolution was changed from to fixed/implemented
• status_id was changed from Open to Closed