WSClean: support relative input and output paths

[anawas]

Summary

If I try to process an existing measurement set with WscleanImageCleaner then Karabo crashes with th error:

subprocess.CalledProcessError: Command 'cd /tmp/karabo-STM-andreas-4S0i7QquzI/WSClean-cleaned-O3U9epMOTu && OPENBLAS_NUM_THREADS=1 wsclean -size 4096 4096 -scale 0.00028647889756541165deg -niter 50000 -mgain 0.8 -auto-threshold 3 measurements.MS' returned non-zero exit status 255.

Steps to reporduce

Assume there is a measurement set measurements.MS from another Karabo workflow. The folder is in my working directory. When I clean the image using the follwing code, the above mentioned error appears:

# Set image property
imaging_npixel = 4096
imaging_cellsize = 5e-6

vis = Visibility(
    ms_file_path="measurements.MS",
)

cleaned_image = WscleanImageCleaner(
    WscleanImageCleanerConfig(
        imaging_npixel=imaging_npixel,
        imaging_cellsize=imaging_cellsize,
    )
)

cleaned_image.create_cleaned_image(
    ms_file_path=vis.ms_file_path,
    output_fits_path="output"
)

# Result
subprocess.CalledProcessError: Command 'cd /tmp/karabo-STM-andreas-4S0i7QquzI/WSClean-cleaned-O3U9epMOTu && OPENBLAS_NUM_THREADS=1 wsclean -size 4096 4096 -scale 0.00028647889756541165deg -niter 50000 -mgain 0.8 -auto-threshold 3 measurements.MS' returned non-zero exit status 255.

Expected result

I want to process dirty images no matter where they are located. Thus, the code above should output the result of the WSClean algorithm in the folder output. This are 5 FITS file.

[anawas]

Workaround

Don't use Karabo. Execute wsclean from command line with

OPENBLAS_NUM_THREADS=1 wsclean -size 4096 4096 -scale 0.00028647889756541165deg -niter 50000 -mgain 0.8 -auto-threshold 3 measurements.MS

[mpluess]

Currently, the ms_file_path needs to be an absolute path for WSClean because we need to do a cd due to the way WSClean works (outputs file to current working dir). I see two options: specifically add support for relative paths or document that an absolute path is expected. Which one do you prefer? Probably option 1?
Also, note that output_fits_path expects the path to the FITS file, e.g. /tmp/test.fits, not an output directory, and that currently, it needs to be an absolute path as well to do what you expect it to do.

[anawas]

Yes, I prefer your option 1 (use relative path).

Also, note that output_fits_path expects the path to the FITS file, e.g. /tmp/test.fits, not an output directory, and that currently, it needs to be an absolute path as well to do what you expect it to do.

This I didn' know. But when I use all your suggestions then it works without an error. We may need to improve the documentation.

[mpluess]

I could see the following TODOs then:

• Support relative input paths for WscleanDirtyImager and WscleanImageCleaner
• Support relative output paths for WscleanDirtyImager and WscleanImageCleaner
• Make output_fits_path documentation more clear (expects a path to a file, not a directory)

[anawas]

Looks like a plan! As it is assigned to me I'll take care of.