Usage¶
MeqSilhouette can be run in a number of ways. They all require that a JSON parset file is passed as the sole argument.
On the local machine¶
If MeqSilhouette is installed on the local machine, it should already have the command meqsilhouette in PATH and can be run as follows:
$ meqsilhouette obs_settings.json
Via Singularity¶
There are two ways to run MeqSilhouette via Singularity. In both cases, it is the responsibility of the user to ensure that the relevant paths in the JSON parset file are writable.
Interactive mode¶
Interactively using the shell option:
$ singularity shell meqsilhouette.sif # drops the user inside the container
> meqsilhouette obs_settings.json
Via Docker¶
There are two ways to run MeqSilhouette via Docker as well. The interactive route is a bit more involved while the command-line mode is more straightforward.
As before, it is the responsibility of the user to ensure that the relevant paths in the JSON parset file are writable.
Interactive mode¶
A docker volume is the best way to share data between the container and the host. First copy the relevant input files to a directory with write access. Assuming that this directory is ~/data, start the docker container as follows:
$ docker run -dit -P -v ~/data:/meqsdata meqsilhouette
where /meqsdata is an arbitrary mount point in the running container to which the host directory ~/data is to be bound. The above command will print the container ID which is a long string of characters (this can also be obtained by typing docker ps -a on the terminal). Once started, attach to the container using the first four characters xxxx of this ID:
$ docker attach xxxx
This will drop the user into the shell from which MeqSilhouette can be run as follows:
$ meqsilhouette /meqsdata/obs_settings.json
Since /meqsdata is where ~/data is mounted, any output files must be written to /meqsdata for them to persist after the container is stopped. If the output files are written elsewhere, the execution will still be successful, but the files will not persist in host storage. To avoid this, the data generated must be manually copied into /meqsdata.
Command-line mode¶
More easily, the following command on the terminal (with all the caveats about paths to input/output files mentioned above) executes MeqSilhouette:
$ docker run -v ~/data:/meqsdata meqsilhouette meqsilhouette /meqsdata/obs_settings.json
Note that the first meqsilhouette is the name of the image to be run and the second meqsilhouette is the command that must be run within the container, since no default entrypoint/command is defined.
IPython/Jupyter Notebook¶
Running MeqSilhouette from any Python interpreter is as easy as firing up the interpreter and typing the following:
from meqsilhouette.driver import run_meqsilhouette
run_meqsilhouette.run_meqsilhouette('/path/to/JSON/parset/file')
The above command will run the default driver script shipped with the source code. This is the same script run by the command meqsilhouette on the command-line in the above cases.
For advanced users¶
By default, the driver script included with the source code will be used to parse the JSON file and generate the synthetic data. Advanced users can construct their own version of the driver script by importing the framework module in their code directly. For instance, additional operations on the Measurement Set such as flagging or averaging can be performed by an enhanced driver script tailored to the needs of the user.