how to access/print a list of a list?

Question

Given;

(setq whole '(group1 group2(element1 element2(suba subb subc)         
   element3) group3))

I would to print some list of that list, like element2 sublist.

How can i do it?

Answer 1

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List Structure Clarification

I suspect you made an error in notating your lisp object. It looks like you were maybe trying to add an identifier to the second group? Check out alists and plists for helpful list structures with keys. They may be correspond to the object you had in mind.

Maybe this will help clarify things. Your list object:

'(group1 group2(element1 element2(suba subb subc) element3) group3)

Should, at a minim, have spaces to make it clear that it is indeed lisp code (and not a mutant child of Scheme and JavaScript):

'(group1 group2 (element1 element2 (suba subb subc) element3) group3)

In an expanded form for readability (with newlines and indentation) expresses exactly the same structure which may not be what you intended:

(Preserving the symbol names in the original post; 'group1' 'group2' are misnomers)

'(
   group1 ; first element of the list (accessed by (elt whole 0) since lists are indexed from zero)
   group2 ; second element (another way of accessing is (nth 1 whole) which is functionally the same as (elt whole 1)
   ( ; third element - is the list you were talking about accessing
     element1 ; first element of your nested list
     element2 ; second element of your nested list
     ( ; third element of the third element
       suba ; first element of the third element of the third element
       subb
       subc
       )
     element3
     )
   group3 ; fourth element of the top-level list
   )

Accessing lists

In addition to elt and nth you should also look at using car and cdr. Once you understand these and their many variations you should have a strong grasp of how lists work in lisp.

(car whole) ; evaluates to the 'group1 symbol you have
(cdr whole) ; evaluates to the rest of the list after 'group1
(cadr whole) ; evaluates to the 'group2 symbol you have
(cddr whole) ; evaluates to the 'group2 symbol you have

Printing

For printing elements of uncertain type you might want to consider using prin1.