Refactor and reorganze.

ngrams/top_comment_phrases.py

@@ -0,0 +1,58 @@
+from pyspark.sql import functions as f
+from pyspark.sql import Window
+from pyspark.sql import SparkSession
+import numpy as np
+
+spark = SparkSession.builder.getOrCreate()
+df = spark.read.text("/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/")
+
+df = df.withColumnRenamed("value","phrase")
+
+# count phrase occurrances
+phrases = df.groupby('phrase').count()
+phrases = phrases.withColumnRenamed('count','phraseCount')
+phrases = phrases.filter(phrases.phraseCount > 10)
+
+
+# count overall
+N = phrases.select(f.sum(phrases.phraseCount).alias("phraseCount")).collect()[0].phraseCount
+
+print(f'analyzing PMI on a sample of {N} phrases') 
+logN = np.log(N)
+phrases = phrases.withColumn("phraseLogProb", f.log(f.col("phraseCount")) - logN)
+
+# count term occurrances
+phrases = phrases.withColumn('terms',f.split(f.col('phrase'),' '))
+terms = phrases.select(['phrase','phraseCount','phraseLogProb',f.explode(phrases.terms).alias('term')])
+
+win = Window.partitionBy('term')
+terms = terms.withColumn('termCount',f.sum('phraseCount').over(win))
+terms = terms.withColumnRenamed('count','termCount')
+terms = terms.withColumn('termLogProb',f.log(f.col('termCount')) - logN)
+
+terms = terms.groupBy(terms.phrase, terms.phraseLogProb, terms.phraseCount).sum('termLogProb')
+terms = terms.withColumnRenamed('sum(termLogProb)','termsLogProb')
+terms = terms.withColumn("phrasePWMI", f.col('phraseLogProb') - f.col('termsLogProb'))
+
+# join phrases to term counts
+
+
+df = terms.select(['phrase','phraseCount','phraseLogProb','phrasePWMI'])
+
+df = df.sort(['phrasePWMI'],descending=True)
+df = df.sortWithinPartitions(['phrasePWMI'],descending=True)
+df.write.parquet("/gscratch/comdata/users/nathante/reddit_comment_ngrams_pwmi.parquet/",mode='overwrite',compression='snappy')
+
+df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_comment_ngrams_pwmi.parquet/")
+
+df.write.csv("/gscratch/comdata/users/nathante/reddit_comment_ngrams_pwmi.csv/",mode='overwrite',compression='none')
+
+df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_comment_ngrams_pwmi.parquet")
+df = df.select('phrase','phraseCount','phraseLogProb','phrasePWMI')
+
+# choosing phrases occurring at least 3500 times in the 10% sample (35000 times) and then with a PWMI of at least 3 yeids about 65000 expressions.
+#
+df = df.filter(f.col('phraseCount') > 3500).filter(f.col("phrasePWMI")>3)
+df = df.toPandas()
+df.to_feather("/gscratch/comdata/users/nathante/reddit_multiword_expressions.feather")
+df.to_csv("/gscratch/comdata/users/nathante/reddit_multiword_expressions.csv")