Hello Lutz,
In the philosophy of Assoc and Lookup the search in nested-list have only the first element as 'key-index. In lists I think all elements are key-indexes
to eighother..thats more logical..? I know..there should be always and index
if more possebilites exist, but in that case always the first is returned.
Searching for the second or third value in a nested list could result
in the following..
(setq X '( ( 1 2 ) ( 3 4 ) ( 5 6 ) ( 7 8 9 ) ))
(assoc 8 X)
>( 7 8 9 )
(lookup 4 X)
> 3
(lookup 8 X)
> 7 true 9 or 7 9
(lookup 7 X)
> true 8 9 or 8 9
Regards, Norman.
Assoc & Lookup
Assoc & Lookup
-- (define? (Cornflakes))
perhaps (ref ...) will do it for you:
(setq X '( ( 1 2 ) ( 3 4 ) ( 5 6 ) ( 7 8 9 ) ))
(ref 8 X) => (3 1)
It gives you a multidimensional index into X, which could have any nesting complexity you want.
You could then extract that element or just look at it:
(pop X '(3 1)) => 8 ; change X
(nth 3 1 X) => 8; leave X how it is
X => ((1 2) (3 4) (5 6) (7 9))
and put something else back:
(push 88 X '(3 1))
X => ((1 2) (3 4) (5 6) (7 88 9))
because 'push' and 'pop' can take multiple indices and they may be in a list, so the result from 'ref' can directly be used in push/pop.
Ref can take any expression as a search key.
(ref '(3 4) X) => (1)
(nth 1 X) => (3 4)
Lutz
(setq X '( ( 1 2 ) ( 3 4 ) ( 5 6 ) ( 7 8 9 ) ))
(ref 8 X) => (3 1)
It gives you a multidimensional index into X, which could have any nesting complexity you want.
You could then extract that element or just look at it:
(pop X '(3 1)) => 8 ; change X
(nth 3 1 X) => 8; leave X how it is
X => ((1 2) (3 4) (5 6) (7 9))
and put something else back:
(push 88 X '(3 1))
X => ((1 2) (3 4) (5 6) (7 88 9))
because 'push' and 'pop' can take multiple indices and they may be in a list, so the result from 'ref' can directly be used in push/pop.
Ref can take any expression as a search key.
(ref '(3 4) X) => (1)
(nth 1 X) => (3 4)
Lutz