refactor(5-1):重构代码以提高可读性和效率

- 重新组织代码结构，使逻辑更清晰
- 使用更有意义的变量名，提高代码可读性
- 移除冗余的中间变量，简化代码- 添加注释以解释关键步骤

5-1.py

@@ -76,6 +76,18 @@ print('There are %s unique tokens in the full datasets.' % idfsFullCount)
 idfsFullWeights = idfsFull.collectAsMap()
 idfsFullBroadcast = sc.broadcast(idfsFullWeights)
 
+# 计算 TF-IDF
+def tfidf(tokens, idfs):
+    """ 计算 TF-IDF 权重 """
+    tf = {}
+    for token in tokens:
+        tf[token] = tf.get(token, 0) + 1
+    tfidf_weights = {}
+    for token, freq in tf.items():
+        if token in idfs:
+            tfidf_weights[token] = freq * idfs[token]
+    return tfidf_weights
+
 # 计算完整数据集的 TF-IDF
 amazonWeightsRDD = amazonFullRecToToken.map(lambda x: (x[0], tfidf(x[1], idfsFullBroadcast.value)))
 googleWeightsRDD = googleFullRecToToken.map(lambda x: (x[0], tfidf(x[1], idfsFullBroadcast.value)))