如何分别计算Scheme中每个子列表与目标列表的匹配得分

Got it, let's work through this problem together. You need to calculate a match score for each family member by counting how many of their items appear in the target list. Here's a straightforward way to implement this in Scheme:

Step 1: Define Your Inputs #

First, let's set up the original family list and target list as you provided:

(define family 
  (list (list 'Daddy 't-shirt 'raincoat 'sunglasses 'pants 'coat 'sneakers)
        (list 'Mamma 'high-heels 'dress 'pants 'sunglasses 'scarf)
        (list 'son 'pants 'sunglasses 'sneakers 't-shirt 'jacket)
        (list 'daughter 'bikini 'Leggings 'sneakers 'blouse 'top)))

(define target (list 'sneakers 'dress 'pants 'sunglasses 'scarf))

Step 2: Create a Helper Function to Count Matches #

We'll start with a helper function that takes a list of items and the target list, then returns the number of items that are present in the target:

(define (count-matches items target)
  ; Filter items that exist in the target list, then get the length of that filtered list
  (length (filter (lambda (item) (member item target)) items)))

• filter goes through each item and keeps only those where (member item target) returns true (meaning the item is in the target list).
• length gives us the count of those matching items, which is our score.

Step 3: Calculate Scores for Each Family Member #

Next, we'll write a function that processes the entire family list, calculating the score for each member:

(define (family-scores family target)
  (map (lambda (member)
         ; Split each member's list into their name (first element) and their items (rest of the list)
         (let ((name (car member))
               (items (cdr member)))
           ; Return a list pairing the name with their calculated score
           (list name (count-matches items target))))
       family))

• map applies our lambda function to every sublist in the family list.
• For each member, we use let to split out their name and items, then compute their score and pair it with their name.

Step 4: Run the Code #

When you call (family-scores family target), you'll get the following result:

((Daddy 3) (Mamma 4) (son 3) (daughter 1))

Let's verify that:

• Daddy has sunglasses, pants, sneakers → 3 points
• Mamma has dress, pants, sunglasses, scarf → 4 points
• Son has pants, sunglasses, sneakers → 3 points
• Daughter only has sneakers → 1 point

That lines up perfectly with what we need!

内容的提问来源于stack exchange，提问作者user9736725