load AHF halo file from different path than snapshot

[Isabel Santos Santos]

Hi,

I wanted to know if it is possible to load an AHF halos file when it is not inside the same directory as the snapshot. I tried using *pathname* (i read about this in a previous question) like this:

h= sim.halos( pathname= path+' name of the halos file' )

but it keeps saying "No halo catalogue found for SimSnap..etc"

thanks for your help,

Isabel

[Andrew Pontzen]

Dear Isabel,

According to the docstring for AHFCatalogue, looks like you have to use ahf_basename instead - see 

https://github.com/pynbody/pynbody/blob/master/pynbody/halo/ahf.py#L39 for details

I guess this is because AHF catalogues are split across multiple files

Hope this helps - Andrew

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[Isabel Santos Santos]

Dear Andrew, thank you, I eventually found it out but it did not work, I had to rename the files. I got the following error:

RuntimeError("Path to AHF (None) is invalid"

Looking at the code, I think pynbody searches for the AHF files with the same basename and if it does not find them, it tries to run AHF, instead of first checking if the ahf_basename keyword was used (?)

thank you

Isabel

[Andrew Pontzen]

Dear Isabel

Yes it looks like it - to get round this you could invoke the AHFCatalogue class directly I.e.

h=pynbody.halo.ahf.AHFCatalogue(f, ahf_basebame=‘...’)

or of course patch the code so it looks for the keyword in can_load (in which case please submit a pull request!)

Best regards

Andrew