BD-exp-9/4-1.py

import math
import re
from pyspark import SparkContext, Broadcast
from pyspark.sql import SparkSession

# 1. 计算点积
def dotprod(a, b):
    """ Compute dot product
    Args:
        a (dict): first dictionary of record to value
        b (dict): second dictionary of record to value
    Returns:
        float: result of the dot product with the two input dictionaries
    """
    sum = 0.0
    for k1, v1 in a.items():
        for k2, v2 in b.items():
            if k1 == k2:
                sum += v1 * v2
    return sum

# 2. 计算范数
def norm(a):
    """ Compute square root of the dot product
    Args:
        a (dict): a dictionary of record to value
    Returns:
        float: norm of the dictionary
    """
    return math.sqrt(dotprod(a, a))

# 3. 计算余弦相似度
def cossim(a, b):
    """ Compute cosine similarity
    Args:
        a (dict): first dictionary of record to value
        b (dict): second dictionary of record to value
    Returns:
        float: cosine similarity value
    """
    return dotprod(a, b) / (norm(a) * norm(b))

# 4. 计算TF-IDF
def tfidf(tokens, idfsDictionary):
    """ Calculate TF-IDF values for token list
    Args:
        tokens (list): list of tokens
        idfsDictionary (dict): IDF values
    Returns:
        dict: dictionary of token -> TF-IDF value
    """
    tf = {}
    for token in tokens:
        tf[token] = tf.get(token, 0) + 1
    total_tokens = len(tokens)
    for token in tf:
        tf[token] = tf[token] / total_tokens
    tfidf = {token: tf[token] * idfsDictionary.get(token, 0) for token in tf}
    return tfidf

# 5. 余弦相似度计算函数
def cosineSimilarity(string1, string2, idfsDictionary):
    """ Compute cosine similarity between two strings using TF-IDF weights
    Args:
        string1 (str): first string
        string2 (str): second string
        idfsDictionary (dict): IDF dictionary
    Returns:
        float: cosine similarity
    """
    tokens1 = tokenize(string1)
    tokens2 = tokenize(string2)
    tfidf1 = tfidf(tokens1, idfsDictionary)
    tfidf2 = tfidf(tokens2, idfsDictionary)
    return cossim(tfidf1, tfidf2)

# 6. Tokenize function (split by spaces or punctuation)
def tokenize(text):
    """ Tokenizes a string into a list of words
    Args:
        text (str): input string
    Returns:
        list: list of tokens (words)
    """
    text = re.sub(r'[^\w\s]', '', text.lower())
    return text.split()

# 7. 计算相似度的RDD处理函数
def computeSimilarity(record, idfsDictionary):
    """ Compute similarity on a combination record
    Args:
        record (tuple): (google record, amazon record)
        idfsDictionary (dict): IDF dictionary
    Returns:
        tuple: (google URL, amazon ID, cosine similarity value)
    """
    googleRec = record[0]
    amazonRec = record[1]
    googleURL = googleRec[0]
    amazonID = amazonRec[0]
    googleValue = googleRec[1]
    amazonValue = amazonRec[1]
    cs = cosineSimilarity(googleValue, amazonValue, idfsDictionary)
    return (googleURL, amazonID, cs)

# 8. 解析黄金标准数据
def parse_goldfile_line(goldfile_line):
    """ Parse a line from the 'golden standard' data file
    Args:
        goldfile_line (str): a line of data
    Returns:
        tuple: ((key, 'gold', 1 if successful or else 0))
    """
    GOLDFILE_PATTERN = '^(.+),(.+)'
    match = re.search(GOLDFILE_PATTERN, goldfile_line)
    if match is None:
        print(f'Invalid goldfile line: {goldfile_line}')
        return (goldfile_line, -1)
    elif match.group(1) == '"idAmazon"':
        print(f'Header datafile line: {goldfile_line}')
        return (goldfile_line, 0)
    else:
        key = f'{match.group(1)} {match.group(2)}'
        return ((key, 'gold'), 1)

# 9. 使用广播变量提高效率
def computeSimilarityBroadcast(record, idfsBroadcast):
    """ Compute similarity on a combination record, using Broadcast variable
    Args:
        record (tuple): (google record, amazon record)
        idfsBroadcast (Broadcast): broadcasted IDF dictionary
    Returns:
        tuple: (google URL, amazon ID, cosine similarity value)
    """
    googleRec = record[0]
    amazonRec = record[1]
    googleURL = googleRec[0]
    amazonID = amazonRec[0]
    googleValue = googleRec[1]
    amazonValue = amazonRec[1]
    cs = cosineSimilarity(googleValue, amazonValue, idfsBroadcast.value)
    return (googleURL, amazonID, cs)

# 主函数，设置Spark上下文和广播变量
if __name__ == "__main__":
    # 创建SparkSession
    spark = SparkSession.builder \
        .appName("TextSimilarity") \
        .getOrCreate()

    sc = spark.sparkContext

    # HDFS路径
    amazon_path = "hdfs://master:9000/user/root/Amazon_small.csv"
    google_path = "hdfs://master:9000/user/root/Google_small.csv"

    # 假设的IDF权重字典
    idfsDictionary = {
        "hello": 1.2,
        "world": 1.3,
        "goodbye": 1.1,
        "photoshop": 2.5,
        "illustrator": 2.7
    }

    # 创建广播变量
    idfsBroadcast = sc.broadcast(idfsDictionary)

    # 加载CSV数据
    amazon_data = spark.read.csv(amazon_path, header=True, inferSchema=True)
    google_data = spark.read.csv(google_path, header=True, inferSchema=True)

    # 假设的列名，根据实际数据进行调整
    amazon_small = amazon_data.select("asin", "description").rdd.map(lambda x: (x[0], x[1]))
    google_small = google_data.select("url", "description").rdd.map(lambda x: (x[0], x[1]))

    # 计算相似度
    cross_small = amazon_small.cartesian(google_small)
    similarities = cross_small.map(lambda x: computeSimilarityBroadcast(x, idfsBroadcast))

    # 打印结果
    similarities.collect()

    # 关闭Spark上下文
    sc.stop()
    spark.stop()