inpointgroup

int  inpointgroup(<geometry>geometry, string groupname, int pointnum)

<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.

Returns

1 if the group exists and the point is in the group, or 0 otherwise.

This can use ad-hoc groups, like 0-3 or @Cd.x>0.5. It matches the SOP group naming convention, in particular that an empty string means all points.