Improve pycbc_plot_vt_ratio

[titodalcanton]

• Expand --help description to make it clear where the necessary files come from.
• Open the input files read-only.
• Replace assertion with a more appropriate argparse error.
• Add metadata to the output file as done in other plotting scripts.
• Add support for writing metadata to PDF images.
• Code cleanup.

[GarethCabournDavies]

A few comments - I guess this is a work in progress as the help messages haven't changed?

[titodalcanton]

A few comments - I guess this is a work in progress as the help messages haven't changed?

I actually changed the description to avoid repeating the same thing twice.

[titodalcanton]

Woops, I just noticed that we have

bin/plotting/pycbc_plot_vt_ratio
bin/workflow_comparisons/offline_search/pycbc_plot_vt_ratio_vs_ifar

should I have modified the latter instead?

[josh-willis]

Woops, I just noticed that we have

bin/plotting/pycbc_plot_vt_ratio
bin/workflow_comparisons/offline_search/pycbc_plot_vt_ratio_vs_ifar

should I have modified the latter instead?

The latter is one that I wrote, and which was used in the review of the GPU implementation. It plots the VT ratio as a function of IFAR rather than at certain specified values; this was specifically requested by the reviewers.

I only wrote it to be compatible with the two-IFO workflow; because the file formats are different for multi-IFO, it would have to be modified to work with it (though I am happy for someone to do that).

[titodalcanton]

Woops, I just noticed that we have

bin/plotting/pycbc_plot_vt_ratio
bin/workflow_comparisons/offline_search/pycbc_plot_vt_ratio_vs_ifar

should I have modified the latter instead?

The latter is one that I wrote, and which was used in the review of the GPU implementation. It plots the VT ratio as a function of IFAR rather than at certain specified values; this was specifically requested by the reviewers.

I only wrote it to be compatible with the two-IFO workflow; because the file formats are different for multi-IFO, it would have to be modified to work with it (though I am happy for someone to do that).

Thanks. I see the two scripts share some code. I will merge this PR now, but it would be good to merge the two scripts at some point.