Merge branch 'master' of code:cdsc_reddit into master

check_comments_shas.py

@@ -5,8 +5,10 @@ import requests
 from os import path
 import hashlib
 
-shasums = requests.get("https://files.pushshift.io/reddit/comments/sha256sums.txt").text
+shasums1 = requests.get("https://files.pushshift.io/reddit/comments/sha256sum.txt").text
+shasums2 = requests.get("https://files.pushshift.io/reddit/comments/daily/sha256sum.txt").text
 
+shasums = shasums1 + shasums2
 dumpdir = "/gscratch/comdata/raw_data/reddit_dumps/comments"
 
 for l in shasums.strip().split('\n'):

checkpoint_parallelsql.sbatch

@@ -0,0 +1,22 @@
+#!/bin/bash
+## parallel_sql_job.sh
+#SBATCH --job-name=tf_subreddit_comments
+## Allocation Definition
+#SBATCH --account=comdata-ckpt
+#SBATCH --partition=ckpt
+## Resources
+## Nodes. This should always be 1 for parallel-sql.
+#SBATCH --nodes=1    
+## Walltime (12 hours)
+#SBATCH --time=12:00:00
+## Memory per node
+#SBATCH --mem=32G
+#SBATCH --cpus-per-task=4
+#SBATCH --ntasks=1
+module load parallel_sql
+
+#Put here commands to load other modules (e.g. matlab etc.)
+#Below command means that parallel_sql will get tasks from the database
+#and run them on the node (in parallel). So a 16 core node will have
+#16 tasks running at one time.
+parallel-sql --sql -a parallel --exit-on-term --jobs 4

comments_2_parquet.sh

@@ -1,5 +1,6 @@
-#!/usr/bin/env bash
+## needs to be run by hand since i don't have a nice way of waiting on a parallel-sql job to complete 
 
+#!/usr/bin/env bash
 echo "#!/usr/bin/bash" > job_script.sh
 echo "source $(pwd)/../bin/activate" >> job_script.sh
 echo "python3 $(pwd)/comments_2_parquet_part1.py" >> job_script.sh

comments_2_parquet_part2.py

@@ -26,4 +26,4 @@ df2.write.parquet("/gscratch/comdata/output/reddit_comments_by_subreddit.parquet
 df = df.repartition('author')
 df3 = df.sort(["author","CreatedAt","subreddit","link_id","parent_id","Year","Month","Day"],ascending=True)
 df3 = df3.sortWithinPartitions(["author","CreatedAt","subreddit","link_id","parent_id","Year","Month","Day"],ascending=True)
-df3.write.parquet("/gscratch/comdata/output/reddit_comments_by_author.parquet", mode='overwrite')
+df3.write.parquet("/gscratch/comdata/output/reddit_comments_by_author.parquet", mode='overwrite',compression='snappy')

helper.py

@@ -40,6 +40,8 @@ def open_input_file(input_filename):
         cmd = ["xzcat",'-dk', '-T 20',input_filename]
     elif re.match(r'.*\.zst',input_filename):
         cmd = ['zstd','-dck', input_filename]
+    elif re.match(r'.*\.gz',input_filename):
+        cmd = ['gzip','-dc', input_filename]
     try:
         input_file = Popen(cmd, stdout=PIPE).stdout
     except NameError as e:

idf_authors.py

@@ -0,0 +1,43 @@
+from pyspark.sql import functions as f
+from pyspark.sql import SparkSession
+
+spark = SparkSession.builder.getOrCreate()
+df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test_authors.parquet_temp/")
+
+max_subreddit_week_authors = df.groupby(['subreddit','week']).max('tf')
+max_subreddit_week_authors = max_subreddit_week_authors.withColumnRenamed('max(tf)','sr_week_max_tf')
+
+df = df.join(max_subreddit_week_authors, ['subreddit','week'])
+
+df = df.withColumn("relative_tf", df.tf / df.sr_week_max_tf)
+
+# group by term / week
+idf = df.groupby(['author','week']).count()
+
+idf = idf.withColumnRenamed('count','idf')
+
+# output: term | week | df
+#idf.write.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test_sorted_tf.parquet_temp",mode='overwrite',compression='snappy')
+
+# collect the dictionary to make a pydict of terms to indexes
+authors = idf.select('author').distinct()
+authors = authors.withColumn('author_id',f.monotonically_increasing_id())
+
+
+# map terms to indexes in the tfs and the idfs
+df = df.join(terms,on='author')
+
+idf = idf.join(terms,on='author')
+
+# join on subreddit/term/week to create tf/dfs indexed by term
+df = df.join(idf, on=['author_id','week','author'])
+
+# agg terms by subreddit to make sparse tf/df vectors
+df = df.withColumn("tf_idf",df.relative_tf / df.sr_week_max_tf)
+
+df = df.groupby(['subreddit','week']).agg(f.collect_list(f.struct('term_id','tf_idf')).alias('tfidf_maps'))
+ 
+df = df.withColumn('tfidf_vec', f.map_from_entries('tfidf_maps'))
+
+# output: subreddit | week | tf/df
+df.write.parquet('/gscratch/comdata/users/nathante/test_tfidf_authors.parquet',mode='overwrite',compression='snappy')

idf_comments.py

@@ -0,0 +1,58 @@
+from pyspark.sql import functions as f
+from pyspark.sql import SparkSession
+
+spark = SparkSession.builder.getOrCreate()
+df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test.parquet_temp")
+
+max_subreddit_week_terms = df.groupby(['subreddit','week']).max('tf')
+max_subreddit_week_terms = max_subreddit_week_terms.withColumnRenamed('max(tf)','sr_week_max_tf')
+
+df = df.join(max_subreddit_week_terms, ['subreddit','week'])
+
+df = df.withColumn("relative_tf", df.tf / df.sr_week_max_tf)
+
+# group by term / week
+idf = df.groupby(['term','week']).count()
+
+idf = idf.withColumnRenamed('count','idf')
+
+# output: term | week | df
+#idf.write.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test_sorted_tf.parquet_temp",mode='overwrite',compression='snappy')
+
+# collect the dictionary to make a pydict of terms to indexes
+terms = idf.select('term').distinct()
+terms = terms.withColumn('term_id',f.monotonically_increasing_id())
+
+
+# print('collected terms')
+
+# terms = [t.term for t in terms]
+# NTerms = len(terms)
+# term_id_map = {term:i for i,term in enumerate(sorted(terms))}
+
+# term_id_map = spark.sparkContext.broadcast(term_id_map)
+
+# print('term_id_map is broadcasted')
+
+# def map_term(x):
+#     return term_id_map.value[x]
+
+# map_term_udf = f.udf(map_term)
+
+# map terms to indexes in the tfs and the idfs
+df = df.join(terms,on='term')
+
+idf = idf.join(terms,on='term')
+
+# join on subreddit/term/week to create tf/dfs indexed by term
+df = df.join(idf, on=['term_id','week','term'])
+
+# agg terms by subreddit to make sparse tf/df vectors
+df = df.withColumn("tf_idf",df.relative_tf / df.sr_week_max_tf)
+
+df = df.groupby(['subreddit','week']).agg(f.collect_list(f.struct('term_id','tf_idf')).alias('tfidf_maps'))
+ 
+df = df.withColumn('tfidf_vec', f.map_from_entries('tfidf_maps'))
+
+# output: subreddit | week | tf/df
+df.write.parquet('/gscratch/comdata/users/nathante/test_tfidf.parquet',mode='overwrite',compression='snappy')

pull_pushshift_comments.sh

@@ -4,8 +4,11 @@ user_agent='nathante teblunthuis <nathante@uw.edu>'
 output_dir='/gscratch/comdata/raw_data/reddit_dumps/comments'
 base_url='https://files.pushshift.io/reddit/comments/'
 
-wget -r --no-parent -A 'RC_20*.bz2' -U $user_agent -P $output_dir -nd -nc $base_url
+wget -r --no-parent -A 'RC_201*.bz2' -U $user_agent -P $output_dir -nd -nc $base_url
-wget -r --no-parent -A 'RC_20*.xz' -U $user_agent -P $output_dir -nd -nc $base_url
+wget -r --no-parent -A 'RC_201*.xz' -U $user_agent -P $output_dir -nd -nc $base_url
-wget -r --no-parent -A 'RC_20*.zst' -U $user_agent -P $output_dir -nd -nc $base_url
+wget -r --no-parent -A 'RC_201*.zst' -U $user_agent -P $output_dir -nd -nc $base_url
 
-./check_comment_shas.py
+# starting in 2020 we use daily dumps not monthly dumps
+wget -r --no-parent -A 'RC_202*.gz' -U $user_agent -P $output_dir -nd -nc $base_url/daily/
+
+./check_comments_shas.py

pull_pushshift_submissions.sh

@@ -11,4 +11,4 @@ wget -r --no-parent -A 'RS_20*.bz2' -U $user_agent -P $output_dir -nd -nc $base_
 wget -r --no-parent -A 'RS_20*.xz' -U $user_agent -P $output_dir -nd -nc $base_url/old_v1_data/
 wget -r --no-parent -A 'RS_20*.zst' -U $user_agent -P $output_dir -nd -nc $base_url/old_v1_data/
 
-./check_submissions_shas.py
+./check_submission_shas.py

run_tf_jobs.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+module load parallel_sql
+source ./bin/activate
+python3 tf_comments.py gen_task_list
+psu --del --Y
+cat tf_task_list | psu --load
+
+for job in $(seq 1 50); do sbatch checkpoint_parallelsql.sbatch; done;

sort_tf_comments.py

@@ -0,0 +1,13 @@
+#!/usr/bin/env python3
+
+from pyspark.sql import functions as f
+from pyspark.sql import SparkSession
+
+spark = SparkSession.builder.getOrCreate()
+df = spark.read.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test.parquet_temp/")
+
+df = df.repartition(2000,'term')
+df = df.sort(['term','week','subreddit'])
+df = df.sortWithinPartitions(['term','week','subreddit'])
+
+df.write.parquet("/gscratch/comdata/users/nathante/reddit_tfidf_test_sorted_tf.parquet_temp",mode='overwrite',compression='snappy')

submissions_2_parquet.sh

@@ -1,10 +1,8 @@
+## this should be run manually since we don't have a nice way to wait on parallel_sql jobs
+
 #!/usr/bin/env bash
 
-echo "!#/usr/bin/bash" > job_script.sh
+./parse_submissions.sh
-echo "source $(pwd)/../bin/activate" >> job_script.sh
-echo "python3 $(pwd)/submissions_2_parquet_part1.py" >> job_script.sh
-
-srun -p comdata -A comdata --nodes=1 --mem=120G --time=48:00:00 job_script.sh
 
 start_spark_and_run.sh 1 $(pwd)/submissions_2_parquet_part2.py
 

submissions_2_parquet_part1.py

@@ -4,7 +4,6 @@
 # 1. from gz to arrow parquet (this script) 
 # 2. from arrow parquet to spark parquet (submissions_2_parquet_part2.py)
 
-import json
 from datetime import datetime
 from multiprocessing import Pool
 from itertools import islice
@@ -12,19 +11,23 @@ from helper import find_dumps, open_fileset
 import pandas as pd
 import pyarrow as pa
 import pyarrow.parquet as pq
+import simdjson
+import fire
+import os
 
+parser = simdjson.Parser()
 
 def parse_submission(post, names = None):
     if names is None:
         names = ['id','author','subreddit','title','created_utc','permalink','url','domain','score','ups','downs','over_18','has_media','selftext','retrieved_on','num_comments','gilded','edited','time_edited','subreddit_type','subreddit_id','subreddit_subscribers','name','is_self','stickied','quarantine','error']
 
     try:
-        post = json.loads(post)
+        post = parser.parse(post)
-    except (json.decoder.JSONDecodeError, UnicodeDecodeError) as e:
+    except (ValueError) as e:
         #        print(e)
         #        print(post)
         row = [None for _ in names]
-        row[-1] = "json.decoder.JSONDecodeError|{0}|{1}".format(e,post)
+        row[-1] = "Error parsing json|{0}|{1}".format(e,post)
         return tuple(row)
 
     row = []
@@ -55,18 +58,11 @@ def parse_submission(post, names = None):
             row.append(post[name])
     return tuple(row)
 
-dumpdir = "/gscratch/comdata/raw_data/reddit_dumps/submissions"
+def parse_dump(partition):
-
-files = list(find_dumps(dumpdir))
-
-pool = Pool(28)
-
-stream = open_fileset(files)
-
-N = 100000
-
-rows = pool.imap_unordered(parse_submission, stream, chunksize=int(N/28))
 
+    N=10000
+    stream = open_fileset([f"/gscratch/comdata/raw_data/reddit_dumps/submissions/{partition}"])
+    rows = map(parse_submission,stream)
     schema = pa.schema([
         pa.field('id', pa.string(),nullable=True),
         pa.field('author', pa.string(),nullable=True),
@@ -96,7 +92,10 @@ schema = pa.schema([
         pa.field('quarantine',pa.bool_(),nullable=True),
         pa.field('error',pa.string(),nullable=True)])
 
-with  pq.ParquetWriter("/gscratch/comdata/output/reddit_submissions.parquet_temp",schema=schema,compression='snappy',flavor='spark') as writer:
+    if not os.path.exists("/gscratch/comdata/output/temp/reddit_submissions.parquet/"):
+        os.mkdir("/gscratch/comdata/output/temp/reddit_submissions.parquet/")
+
+    with pq.ParquetWriter(f"/gscratch/comdata/output/temp/reddit_submissions.parquet/{partition}",schema=schema,compression='snappy',flavor='spark') as writer:
         while True:
             chunk = islice(rows,N)
             pddf = pd.DataFrame(chunk, columns=schema.names)
@@ -107,3 +106,13 @@ with  pq.ParquetWriter("/gscratch/comdata/output/reddit_submissions.parquet_temp
 
         writer.close()
 
+def gen_task_list(dumpdir="/gscratch/comdata/raw_data/reddit_dumps/submissions"):
+    files = list(find_dumps(dumpdir,base_pattern="RS_20*.*"))
+    with open("parse_submissions_task_list",'w') as of:
+        for fpath in files:
+            partition = os.path.split(fpath)[1]
+            of.write(f'python3 submissions_2_parquet_part1.py parse_dump {partition}\n')
+
+if __name__ == "__main__":
+    fire.Fire({'parse_dump':parse_dump,
+              'gen_task_list':gen_task_list})

submissions_2_parquet_part2.py

@@ -17,7 +17,7 @@ conf = conf.set('spark.sql.crossJoin.enabled',"true")
 conf = conf.set('spark.debug.maxToStringFields',200)
 sqlContext = pyspark.SQLContext(sc)
 
-df = spark.read.parquet("/gscratch/comdata/output/reddit_submissions_by_subreddit.parquet")
+df = spark.read.parquet("/gscratch/comdata/output/temp/reddit_submissions.parquet/")
 
 df = df.withColumn("subreddit_2", f.lower(f.col('subreddit')))
 df = df.drop('subreddit')
@@ -32,13 +32,11 @@ df = df.withColumn("subreddit_hash",f.sha2(f.col("subreddit"), 256)[0:3])
 df = df.repartition("subreddit")
 df2 = df.sort(["subreddit","CreatedAt","id"],ascending=True)
 df2 = df.sortWithinPartitions(["subreddit","CreatedAt","id"],ascending=True)
-df2.write.parquet("/gscratch/comdata/output/reddit_submissions_by_subreddit.parquet2", mode='overwrite',compression='snappy')
+df2.write.parquet("/gscratch/comdata/output/temp/reddit_submissions_by_subreddit.parquet2", mode='overwrite',compression='snappy')
 
 
 # # we also want to have parquet files sorted by author then reddit. 
 df = df.repartition("author")
 df3 = df.sort(["author","CreatedAt","id"],ascending=True)
 df3 = df.sortWithinPartitions(["author","CreatedAt","id"],ascending=True)
-df3.write.parquet("/gscratch/comdata/output/reddit_submissions_by_author.parquet2", mode='overwrite',compression='snappy')
+df3.write.parquet("/gscratch/comdata/output/temp/reddit_submissions_by_author.parquet2", mode='overwrite',compression='snappy')
-
-os.remove("/gscratch/comdata/output/reddit_submissions.parquet_temp")

tf_comments.py

@@ -0,0 +1,191 @@
+#!/usr/bin/env python3
+import pyarrow as pa
+import pyarrow.dataset as ds
+import pyarrow.parquet as pq
+from itertools import groupby, islice, chain
+import fire
+from collections import Counter
+import pandas as pd
+import os
+import datetime
+import re
+from nltk import wordpunct_tokenize, MWETokenizer, sent_tokenize
+from nltk.corpus import stopwords
+from nltk.util import ngrams
+import string
+from random import random
+
+# remove urls
+# taken from https://stackoverflow.com/questions/3809401/what-is-a-good-regular-expression-to-match-a-url
+urlregex = re.compile(r"[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)")
+
+# compute term frequencies for comments in each subreddit by week
+def weekly_tf(partition, mwe_pass = 'first'):
+    dataset = ds.dataset(f'/gscratch/comdata/output/reddit_comments_by_subreddit.parquet/{partition}', format='parquet')
+
+    if not os.path.exists("/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/"):
+        os.mkdir("/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/")
+
+    if not os.path.exists("/gscratch/comdata/users/nathante/reddit_tfidf_test_authors.parquet_temp/"):
+        os.mkdir("/gscratch/comdata/users/nathante/reddit_tfidf_test_authors.parquet_temp/")
+
+    ngram_output = partition.replace("parquet","txt")
+
+    if os.path.exists(f"/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/{ngram_output}"):
+        os.remove(f"/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/{ngram_output}")
+    
+    batches = dataset.to_batches(columns=['CreatedAt','subreddit','body','author'])
+
+
+    schema = pa.schema([pa.field('subreddit', pa.string(), nullable=False),
+                        pa.field('term', pa.string(), nullable=False),
+                        pa.field('week', pa.date32(), nullable=False),
+                        pa.field('tf', pa.int64(), nullable=False)]
+    )
+
+    author_schema = pa.schema([pa.field('subreddit', pa.string(), nullable=False),
+                               pa.field('author', pa.string(), nullable=False),
+                               pa.field('week', pa.date32(), nullable=False),
+                               pa.field('tf', pa.int64(), nullable=False)]
+    )
+
+    dfs = (b.to_pandas() for b in batches)
+
+    def add_week(df):
+        df['week'] = (df.CreatedAt - pd.to_timedelta(df.CreatedAt.dt.dayofweek, unit='d')).dt.date
+        return(df)
+
+    dfs = (add_week(df) for df in dfs)
+
+    def iterate_rows(dfs):
+        for df in dfs:
+            for row in df.itertuples():
+                yield row
+
+    rows = iterate_rows(dfs)
+
+    subreddit_weeks = groupby(rows, lambda r: (r.subreddit, r.week))
+
+    if mwe_pass != 'first':
+        mwe_dataset = pd.read_feather(f'/gscratch/comdata/users/nathante/reddit_multiword_expressions.feather')
+        mwe_dataset = mwe_dataset.sort_values(['phrasePWMI'],ascending=False)
+        mwe_phrases = list(mwe_dataset.phrase)
+        mwe_phrases = [tuple(s.split(' ')) for s in mwe_phrases]
+        mwe_tokenizer = MWETokenizer(mwe_phrases)
+        mwe_tokenize = mwe_tokenizer.tokenize
+    
+    else:
+        mwe_tokenize = MWETokenizer().tokenize
+
+    def remove_punct(sentence):
+        new_sentence = []
+        for token in sentence:
+            new_token = ''
+            for c in token:
+                if c not in string.punctuation:
+                    new_token += c
+            if len(new_token) > 0:
+                new_sentence.append(new_token)
+        return new_sentence
+
+
+    stopWords = set(stopwords.words('english'))
+
+    # we follow the approach described in datta, phelan, adar 2017
+    def my_tokenizer(text):
+        # remove stopwords, punctuation, urls, lower case
+        # lowercase        
+        text = text.lower()
+
+        # remove urls
+        text = urlregex.sub("", text)
+
+        # sentence tokenize
+        sentences = sent_tokenize(text)
+
+        # wordpunct_tokenize
+        sentences = map(wordpunct_tokenize, sentences)
+
+        # remove punctuation
+                        
+        sentences = map(remove_punct, sentences)
+
+        # remove sentences with less than 2 words
+        sentences = filter(lambda sentence: len(sentence) > 2, sentences)
+
+        # datta et al. select relatively common phrases from the reddit corpus, but they don't really explain how. We'll try that in a second phase.
+        # they say that the extract 1-4 grams from 10% of the sentences and then find phrases that appear often relative to the original terms
+        # here we take a 10 percent sample of sentences 
+        if mwe_pass == 'first':
+            sentences = list(sentences)
+            for sentence in sentences:
+                if random() <= 0.1:
+                    grams = list(chain(*map(lambda i : ngrams(sentence,i),range(4))))
+                    with open(f'/gscratch/comdata/users/nathante/reddit_comment_ngrams_10p_sample/{ngram_output}','a') as gram_file:
+                        for ng in grams:
+                            gram_file.write(' '.join(ng) + '\n')
+                for token in sentence:
+                    if token not in stopWords:
+                        yield token
+
+        else:
+            # remove stopWords
+            sentences = map(mwe_tokenize, sentences)
+            sentences = map(lambda s: filter(lambda token: token not in stopWords, s), sentences)
+            for sentence in sentences:
+                for token in sentence:
+                    yield token
+
+    def tf_comments(subreddit_weeks):
+        for key, posts in subreddit_weeks:
+            subreddit, week = key
+            tfs = Counter([])
+            authors = Counter([])
+            for post in posts:
+                tokens = my_tokenizer(post.body)
+                tfs.update(tokens)
+                authors.update([post.author])
+
+            for term, tf in tfs.items():
+                yield [True, subreddit, term, week, tf]
+
+            for author, tf in authors.items():
+                yield [False, subreddit, author, week, tf]
+
+    outrows = tf_comments(subreddit_weeks)
+
+    outchunksize = 10000
+
+    with pq.ParquetWriter(f"/gscratch/comdata/users/nathante/reddit_tfidf_test.parquet_temp/{partition}",schema=schema,compression='snappy',flavor='spark') as writer, pq.ParquetWriter(f"/gscratch/comdata/users/nathante/reddit_tfidf_test_authors.parquet_temp/{partition}",schema=author_schema,compression='snappy',flavor='spark') as author_writer:
+    
+        while True:
+
+            chunk = islice(outrows,outchunksize)
+            chunk = (c for c in chunk if c[1] is not None)
+            pddf = pd.DataFrame(chunk, columns=["is_token"] + schema.names)
+            author_pddf = pddf.loc[pddf.is_token == False, schema.names]
+            pddf = pddf.loc[pddf.is_token == True, schema.names]
+            author_pddf = author_pddf.rename({'term':'author'}, axis='columns')
+            author_pddf = author_pddf.loc[:,author_schema.names]
+
+            table = pa.Table.from_pandas(pddf,schema=schema)
+            author_table = pa.Table.from_pandas(author_pddf,schema=author_schema)
+            if table.shape[0] == 0:
+                break
+            writer.write_table(table)
+            author_writer.write_table(author_table)
+            
+        writer.close()
+        author_writer.close()
+
+
+def gen_task_list(mwe_pass='first'):
+    files = os.listdir("/gscratch/comdata/output/reddit_comments_by_subreddit.parquet/")
+    with open("tf_task_list",'w') as outfile:
+        for f in files:
+            if f.endswith(".parquet"):
+                outfile.write(f"./tf_comments.py weekly_tf --mwe-pass {mwe_pass} {f}\n")
+
+if __name__ == "__main__":
+    fire.Fire({"gen_task_list":gen_task_list,
+               "weekly_tf":weekly_tf})

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")