Bringing it all Together: Family Trees CMSC 11500 Introduction to Computer Programming October 18, 2002

Roadmap An integrated example: Family trees Building the data definition Structures of structures Using the data From data definition to template Traversing family trees Heredity: traits Simplifying with Let

Family Trees Each child has: mother, father, & some attributes - e.g. birthdate, hair color, eye color Granny: Eyes: Brown Grandpa: Eyes: Blue Mom: Eyes: Green Dad: Eyes: Brown Jane: Eyes: Hazel John: Eyes: Brown

Data Definition A family-tree is ‘unknown, or (make-ft name eye-color mother father) where name, eye-color are symbols; mother,father are family-tree (define-struct ft (name eye-color mother father) (make-ft ‘Granny ‘Blue ‘unknown ‘unknown) (make-ft ‘John ‘Brown (make-ft ‘Mom ‘Green (…) (…))…..)

Defining Functions: Data definition to Template A family-tree is: - unknown, or - (make-ft name eye-color mother father) Questions: How many kinds of family-tree? # pieces in 1st part? # pieces in 2nd part? Self-references? - Do What?

Defining Functions: Data definition to Template A family-tree is: - unknown, or - (make-ft name eye-color mother father) Template: (define (fn-for-f-tree aft) (cond ((eq? ‘unknown aft) …) ((ft? aft) … (ft-name aft)… … (ft-eye-color aft)… … (fn-for-f-tree (ft-mother aft)). … (fn-for-f-tree (ft-father aft))..

Things to do with Family Trees Find ancestor(s) with certain traits e.g. eye-color, born before some date Find all traits for all relatives Compute relations between individuals Determine if they are related by blood

Blue-Eyed Ancestor Contract:b-e-a: family-tree ->symbol Purpose: Find a blue-eyed ancestor

Blue-eyed-ancestor (define (b-e-a aft) (cond ((eq? ‘unknown aft) #f) ((ft? aft) (if (eq? (ft-eye-color aft) ‘blue) (ft-name aft) (let ((b-e-m (b-e-a (ft-mother aft))) (b-e-f (b-e-a (ft-father aft)))) (cond ((symbol? b-e-m) b-e-m) ((symbol? b-e-f) b-e-f) (else #f))))))

All-blue-eyed-ancestors Get all ancestors (not just first) Contract: a-b-e-a: family-tree -> (listof symbol) Purpose: Find all blue-eyed-ancestors Helper: “append” (append ‘(a b c) ‘(a b c)) -> ‘(a b c) (define (append list1 list2) (cond ((null? list1) list2) (else (cons (car list1) (append (cdr list1) list2)))

All-blue-eyed-ancestors (define (a-b-e-a aft) (cond ((eq? ‘unknown aft) ‘()) ((ft? aft) (if (eq? (ft-eye-color aft) ‘blue) (cons (ft-name aft) (append (a-b-e-a (ft-mother aft)) (a-b-e-a (ft-father aft)))) (append (a-b-e-a (ft-mother aft)) (a-b-e-a (ft-father aft))))))))

All-blue-eyed-ancestors (define (a-b-e-a aft) (cond ((eq? ‘unknown aft) ‘()) (else (let ((in-parents (append (a-b-e-a (ft-mother aft)) (a-b-e-a (ft-father aft))))) (if (eq? (ft-eye-color aft) ‘blue) (cons (ft-name aft) in-parents) in-parents))))))

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