nverticesgroup

int  nverticesgroup(<geometry>geometry, string groupname)

<geometry>

When running in the context of a node (such as a wrangle SOP), this argument can be an integer representing the input number (starting at 0) to read the geometry from.

Alternatively, the argument can be a string specifying a geometry file (for example, a .bgeo) to read from. When running inside Houdini, this can be an op:/path/to/sop reference.

groupname

A group name or ad-hoc group, like 0-3 or @Cd.x>0.5. This matches the SOP group naming convention, in particular that an empty string means all vertices.