Edge selector needed

[gitterman]

I am using CQ Editor 0.5.dev() and I have the following simple part.
part = ( cq.Workplane("XY") .circle(20) .circle(15) .extrude(10) .copyWorkplane(cq.Workplane("YZ", origin=(15, 0, 5))) .rect(10, 10) .extrude(40) )
I am trying to fillet the vertical edges at the outer circular circumference where the rectangular extrusion intersects the cylinder.
How can I select only these?

[lorenzncode]

Here is an example using siblings to select the two edges:

import cadquery as cq

part1 = cq.Workplane().circle(20).circle(15).extrude(10)

part2 = cq.Workplane("YZ", origin=(15, 0, 5)).rect(10, 10).extrude(40)

part = part1 + part2

part = (
    part.edges("%CIRCLE")  # edges of the ring
    .edges(cq.selectors.RadiusNthSelector(-1))  # outer edges of ring
    .siblings("Vertex")  # sibling edges with common vertex
    .edges("|Z")  # the edges parallel to Z direction
    .fillet(2.0)
)

[gitterman]

Thanks a lot for the quick solution.
It gave me some better insights into the selectors.
My workaround was to add a small fillet to the face ">X" to isolate the intersecting edge like this:
part = (part.faces( ">X" ).fillet( 0.2 ) # isolate the intersecting edge
.edges( "|Z" ).fillet( 5 )
)
It creates unwanted fillets, though.
I am wondering if there is an option for the edges( "|Z" ) which selects only specific elements from a resulting list of edges.

[adam-urbanczyk]

For this particular geometry you can simply to use selector chaining:

part.edges('|Z').edges('>>X[-2]').fillet(2)

[gitterman]

Great, that is exactly what I was looking for.
I had read the docs at https://cadquery.readthedocs.io/en/latest/selectors.html but only tried with constructs like ">X[-2]", which always gave me "ValueError: Can not return the Nth element of an empty list".
It still isn't clear to me, though, why the "DirectionNthSelector" doesn't work here whereas the "CenterNthSelector" does.