How to call a function within class?

Since these are member functions, call it as a member function on the instance, self.

def isNear(self, p):
    self.distToPoint(p)
    ...

That doesn't work because distToPoint is inside your class, so you need to prefix it with the classname if you want to refer to it, like this: classname.distToPoint(self, p). You shouldn't do it like that, though. A better way to do it is to refer to the method directly through the class instance (which is the first argument of a class method), like so: self.distToPoint(p).