idf_comments.py

   1 from pyspark.sql import functions as f
   2 from pyspark.sql import SparkSession
   3
   4 spark = SparkSession.builder.getOrCreate()
   5 df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test.parquet_temp")
   6
   7 max_subreddit_week_terms = df.groupby(['subreddit','week']).max('tf')
   8 max_subreddit_week_terms = max_subreddit_week_terms.withColumnRenamed('max(tf)','sr_week_max_tf')
   9
  10 df = df.join(max_subreddit_week_terms, ['subreddit','week'])
  11
  12 df = df.withColumn("relative_tf", df.tf / df.sr_week_max_tf)
  13
  14 # group by term / week
  15 idf = df.groupby(['term','week']).count()
  16
  17 idf = idf.withColumnRenamed('count','idf')
  18
  19 # output: term | week | df
  20 #idf.write.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test_sorted_tf.parquet_temp",mode='overwrite',compression='snappy')
  21
  22 # collect the dictionary to make a pydict of terms to indexes
  23 terms = idf.select('term').distinct()
  24 terms = terms.withColumn('term_id',f.monotonically_increasing_id())
  25
  26
  27 # print('collected terms')
  28
  29 # terms = [t.term for t in terms]
  30 # NTerms = len(terms)
  31 # term_id_map = {term:i for i,term in enumerate(sorted(terms))}
  32
  33 # term_id_map = spark.sparkContext.broadcast(term_id_map)
  34
  35 # print('term_id_map is broadcasted')
  36
  37 # def map_term(x):
  38 #     return term_id_map.value[x]
  39
  40 # map_term_udf = f.udf(map_term)
  41
  42 # map terms to indexes in the tfs and the idfs
  43 df = df.join(terms,on='term')
  44
  45 idf = idf.join(terms,on='term')
  46
  47 # join on subreddit/term/week to create tf/dfs indexed by term
  48 df = df.join(idf, on=['term_id','week','term'])
  49
  50 # agg terms by subreddit to make sparse tf/df vectors
  51 df = df.withColumn("tf_idf",df.relative_tf / df.sr_week_max_tf)
  52
  53 df = df.groupby(['subreddit','week']).agg(f.collect_list(f.struct('term_id','tf_idf')).alias('tfidf_maps'))
  54
  55 df = df.withColumn('tfidf_vec', f.map_from_entries('tfidf_maps'))
  56
  57 # output: subreddit | week | tf/df
  58 df.write.parquet('/gscratch/comdata/users/nathante/test_tfidf.parquet',mode='overwrite',compression='snappy')