List -> list containing even indexes

mapcar(lambda((items) list(car(items) caddr(items) nth(4 items) nth(6 items))) myList)

 Ок and if quantity of members of list equally N and me it is necessary to receive list containing every second?

Best regard

Slawa 

My solution, don't know if this is what your exactly looking for.

 Bernd

let( ( myList listLegth evenIndexList oddIndexList )

myList = list( "one" "two" "three" "four" "five" "six" "seven" )

listLegth = length( myList )

for( n 1 listLegth
  cond(
    ( evenp( n )
      evenIndexList = nconc( evenIndexList list( nthelem( n myList ) ) )
    )
    ( oddp( n )
      oddIndexList = nconc( oddIndexList list( nthelem( n myList ) ) )
    )
  )
)

printf( "evenIndexList: %L\n" evenIndexList )
printf( "oddIndexList: %L\n" oddIndexList )

)

 Many thanks Berndf it that is necessary.

Best regards

Slawa 

Hi Slawa,

How about the following?

myList = '(1 2 3 4 5 6 7 8)
=> (1 2 3 4 5
    6 7 8
   )
idx = 0
setof(elem foreach(mapcar item myList evenp(idx++)&&item) elem)
=> (1 3 5 7)

This iterates over the list using foreach mapcar and the result would look like (1 nil 3 nil ...) and then the setof filters this list to remove any 'nil' values.  The input list does not have to be numeric, only the variable idx is required to be numeric. Change the evenp predicate to oddp if the even indexes are needed.

Regards,

Lawrence.

 Thanks Lawrence.
This variant too approaches also it a bit easier offered above.

Best regards

Slawa