Extend (selection operator)
This page is about a selection operator. For the API function with the same name, see extend.
The selection operator extend is part of the PyMOL selection language and grows an atom selection based on covalent bonds.
s1 extend X
Where s1 is a selection expression and X is the number of bonds.
The behavior is illustrated on residue 64 of PDB file 1KAO where we initially select one atom and then "extend" that selection by one and three covalent bonds.
select (resi 64 and name CZ)
select (resi 64 and name CZ) extend 1
select (resi 64 and name CZ) extend 3