a=list(p1)

b=list(p2)

c= [i for i in a if i not in b]

Dear Leo,

I can think of two ways to overcome the issue.

A simple way around the issue is to convert the edge sequences p1 and p2 into lists and removing the entities of p2 from p1.

p1l,p2l=list(p1),list(p2)

for i in p2l:

p1l.remove(i)

#

However, this results in a list of the individual edges which might be a problem if you are using it for further operations (like creating a set for example).

Another way is to define the bounding box in such a way as to exclude the undesired edges. You can use multiple bounding boxes to achieve the above result (since addition is straightforward). For your example, the following code would select the desired edges.

p1=p.edges.getByBoundingBox(-1,-1,-1,-0.74,1,1)+p.edges.getByBoundingBox(-0.26,-1,-1,0.26,-0.26,1)+p.edges.getByBoundingBox(-0.26,0.26,-1,0.26,1,1)+p.edges.getByBoundingBox(0.26,-1,-1,1,1,1)

Regards,

Abhilash

a=list(p1)

b=list(p2)

c= [i for i in a if i not in b]