How do I get an item from a list at a given index in racket language?

list, racket, scheme

Solution

Example:

> (list-ref '(a b c d e f) 2)
'c

See:

http://docs.racket-lang.org/reference/pairs.html

Problem

I'm trying to get an item from a list at a given index for a loop statement. ``` (define decision-tree-learning (lambda (examples attribs default) (cond [(empty? examples) default] [(same-classification? examples) (caar examples)] ; returns the classification [else (lambda () (let ((best (choose-attribute attributes examples)) (tree (make-tree best)) (m (majority-value examples)) (i 0) (countdown (length best)) ; starts at lengths and will decrease by 1 (let loop() (let example-sub ; here, totally stuck now ; more stuff (set! countdown (- countdown 1)) ; more stuff )))))]))) ``` In this case, `best` is the list and I need to get its value at the `countdown` index. Could you help me on that?

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