It is not possible to copy an arbitrary key/object from the input P-frame to the output P-frame. There is also no warranty that a particle extracted with the --extra option will have a corresponding object in the output P-frame. If you need such a feature, or you want to improve this behavior, feel free to file a pull request!
Ideally:
[ ] it should be possible to write out arbitrary keys even if they are not I3Particle objects;
[ ] all objects corresponding to I3Particle-s extracted with --extra should be written in the output P frame.
None of these should be particularly hard to implement but I did not want to further delay the merge of #15
Quoting from the current
README(following #15):Ideally:
I3Particleobjects;I3Particle-s extracted with--extrashould be written in the output P frame.None of these should be particularly hard to implement but I did not want to further delay the merge of #15