Hi! I would like to create a function to copy the torsion angle from a model to another one. The function would take in argument the model ID of the reference and target model (<int>) and the residue id (<int>). I looked a bit at the scripts available in [ https://rbvi.github.io/chimerax-recipes/ | https://rbvi.github.io/chimerax-recipes/ ] to have an idea of how to add function in ChimeraX, but I'm currently stuck at "how to get the list of atoms from a selection string ?". Here's my current script from chimerax.core.commands import run def copy_torsion(session, model1, model2, residue): selection = f"torsion #{model2}:{residue}@n,ca,c:{residue+1}@n" from chimerax.atomic import AtomsArg atoms = AtomsArg(selection) from chimerax.geometry import dihedral cur_torsion = dihedral([*a.scene_coord for a in atoms]) torsion=run(session, f"torsion #{model1}:{residue}@n,ca,c:{residue+1}@n {cur_torsion}") def register_command(logger): from chimerax.core.commands import CmdDesc, register, FloatArg, IntArg, BoolArg, Color8Arg, StringArg from chimerax.atomic import AtomsArg desc = CmdDesc(required = [ ('model1', IntArg), ('model2', IntArg), ('residue', IntArg), ], synopsis='Copy torsion angle') register('copyTorsion', desc, copy_torsion, logger=logger) register_command(session) Thank you for your help :) Best regards, Thibault. -- Thibault Tubiana, PhD Postdoctoral Fellow @ [ https://www.i2bc.paris-saclay.fr/equipe-interactions-and-assembly-mechanisms... | IMAPP ] Institute for integrative biology of the cell ( [ https://www.i2bc.paris-saclay.fr/ | I2BC ] ) - CNRS UMR 9198 CEA Saclay, 91191 Gif sur Yvette - Bât 532 pce 34 Web Site: [ http://www.tubiana.me/ | http://www.tubiana.me/ ]