Never mind, I forgot to import the module Best, Kevin ________________________________ From: Kevin Wang Sent: Friday, December 6, 2019 6:30 PM To: chimera-users@cgl.ucsf.edu <chimera-users@cgl.ucsf.edu> Subject: Contact_area Arguments Hi, I am using python to calculate contact area between 2 chains. My code is as follows p1, p2 = [s.surface_piece for s in openModels.list(modelTypes=[MSMSModel])] y = measure.contact_area(p1, p2, 2.5) However, this returns the error: TypeError: contact_area() takes at least 4 arguments (3 given) This is the function for contact_area def contact_area(p1, p2, d, color = None, offset = None, slab = None, smooth = False, optimize = True): What is the 4th required argument? Best, Kevin