Dupes in list of lists?

List variable BoundList contains multiple paired lists of entity names.
Ename
7ef71e08 appears twice as a second item and I need a way, after the
list is built, to detect such duplicates. Any suggestions? Len Miller.

(
(<Entity name: 7ef71e00> <Entity name: 7ef71df8>)
(<Entity name: 7ef71e10> <Entity name: 7ef71e08>)
(<Entity name: 7ef71e18> <Entity name: 7ef71e08>)
(<Entity name: 7ef71e18> <Entity name: 7ef71e10>)
)

p.s. Yes, 7ef71e18 is a dupe as well but first item dupes are not an issue
here.

 

In general, problems like this are solved in the code
that creates the list, rather than after the fact.

Where does the list come from? Under most circumstances,
construction of the list can be constrained to avoid
adding duplicate elements quite easily.

 

(mapcar 'cadr BoundList) returns a list of all secondary elements. You
simply need to check each item of that list if it is a member of CDR
of that list. Here the duplicate entities are stored in variable
duplist:

(setq blist2 (mapcar 'cadr BoundList))
(while (and (setq first (car blist2)) (setq blist2 (cdr blist2)))
(if (member first blist2)
(setq duplist (cons first duplist))
)
)

Tom Berger

 

you can begin to constructing a second list very easily

say l1 and l2

(foreach i1 l1
(if (= (member i1 l2) nil)
(setq l2 (cons i1 l2))
)
)



Jamie Duncan

Consulting - If you're not part of the solution, there's good money in
prolonging the problem.

 

I think I understand your point.

For example, take that list of lists. By the time I'm ready to place list
number 3 inside, the main list looks like:
(
(<Entity name: 7ef71e00> <Entity name: 7ef71df8>)
(<Entity name: 7ef71e10> <Entity name: 7ef71e08>)
)
List number 3 is ready, (<Entity name: 7ef71e18> <Entity name: 7ef71e08>)
and can manually see that there is a dupe ready to happen. But I don't know
how to Lisp it for in reality there may be 30 members in the main list and
dupes will not necessarily be contiguous as in the case above.

 

Let's say your list is called Pairs, and the pair to be added is called Pair.
Then...
(or
(vl-position (cadr Pair)(mapcar 'cadr Pairs))
(setq Pairs (cons Pair Pairs))
)

 

Yes, you are correct that the second element must be unique so I will take
your tip in reversing their order -- then see if I can understand and follow
your recipe to solve my problem.