ERROR: r.distance: Sorry, <output> is not a valid parameter[Bug]

[julychee]

Hello!

For an assignment I am using QGIS (on macOS 10.14.6 with Grass 7 version 2.0) and I am wanting to use r.distance to calculate the distance between points and an area (which i'm assuming works but i'm not even sure because I can't run r.distance). Once I input my parameters and run the tool, it gives me the following error written in red: ERROR: r.distance: "Sorry, is not a valid parameter". In the log file I can also see another error after it executes the folder in which r.distance is, saying "NameError: name 'file' is not defined". In addition, the log says that there is an output as a txt file, but it is not created.

Steps:

1. open r.distance
2. select my two raster layers, leave the field separator as is, and choose my output as distance as "desc".
3. run r.distance
4. see error

I will add screenshots of the log as a resulting of running r.distance.
My question is, what does that error message mean? Is it something I can fix?If not, is there another tool I can use that serves the same purpose?

Thank you!

[neteler]

To me it looks like a wrong definition in the respective QGIS control file:
https://github.com/qgis/QGIS/blob/2338b1491c2762eac7ed0693fb11e1057695ff27/python/plugins/processing/algs/grass7/description/r.distance.txt#L10

since r.distance does not have an output parameter, see:
https://grass.osgeo.org/grass78/manuals/r.distance.html

(unless there is an extra trick in the QGIS processing interface to deal with such text outputs sent to the standard output like in this case...)

[nilason]

This is a QGIS issue.

(unless there is an extra trick in the QGIS processing interface to deal with such text outputs sent to the standard output like in this case...)

Yes, the standard output is supposed to be redirected to a text file as declared in r.distance.txt:

QgsProcessingParameterFileDestination|output|Distance|Txt files (*.txt)|None|False

I'm not sure how that is intended to work, but as a workaround, changing that line to:

QgsProcessingParameterFileDestination|html|Distance|Html files (*.html)|distance.html|False

the command works (output will be in html format though).

@julychee that file is probably located here:

/Applications/QGIS3.10.app/Contents/Resources/python/plugins/processing/algs/grass7/description/r.distance.txt

[nilason]

Reported the issue with QGIS.

[julychee]

Thank you!

When changing the command mentioned above by @nilason, the output is now created as an html. However, I am now getting a different error, which leads the html output to be empty:

ERROR: Raster map <rast_5ec28a490abe839> is not CELL

I am not sure I understand what this means. I didn't have this error before.

[nilason]

This issue has been closed downstream qgis/QGIS#36520 with fix qgis/QGIS#36644, which was also backported to QGIS 3.10. This issue may be closed.

@julychee Thanks for your report! I don't know what caused your second issue. Please take a look at manual of r.distance, maybe that can give a clue. If not, consider file a new report at https://github.com/qgis/QGIS/.