## Residue.index — internal integer index

> This is the index used internally to identify the residue; residues are numbered sequentially starting from 1.

Example: examples/commands/write_pdb_xref.py

      # This demonstrates relating PDB residue numbers with residue indices.

      from modeller import *

      log.verbose()
      env = environ()
      env.io.atom_files_directory = ['../atom_files']

      mdl = model(env, file='2abx')

      print("Mapping from residue indices to PDB residue and chain names:")
      for r in mdl.residues:
          print("%6d   %3s:%s   %s" % (r.index, r.num, r.chain.name, r.pdb_name))