RFE: allow reassignment of chain for residues

[Tristan Croll]

Not particularly urgent, but it would certainly be useful to have this ability at some point. It's surprising how often the need can come up (particularly when handling ions, waters, ligands etc.). In the early stages of model building it can be difficult to work out which peptide fragments belong to which chain, so reassignment comes up regularly in these situations. Similarly, being able to change the chain_id of a chain would be handy (e.g. for re-ordering IDs into a more logical sequence).

[pett]

Allowing reassignment of numbers is very easy, so it will probably happen within our lifetimes. :-) Chain IDs is somewhat trickier in that Chains are their own objects and changing IDs may force segments into/out of a Chain if the Chain is composed of multiple disjoint polymeric segments. Nonetheless, doable -- just less simple than changing the numbering. You need to be aware that changing residue numbering will do nothing to the ordering of the residues -- you have to use Structure.reorder_residues() for that.

--Eric

[pett]

Renumbering should also have an option to try to adjust for missing residues.

[pett]

This is now just reassignment of chain. Renumbering is #2528.

[pett]

#2528 handled whole-chain chain ID changes, so this ticket is now only for partial-chain changes.