submissions_2_parquet_part1.py

   1 #!/usr/bin/env python3
   2
   3 # two stages:
   4 # 1. from gz to arrow parquet (this script)
   5 # 2. from arrow parquet to spark parquet (submissions_2_parquet_part2.py)
   6
   7 import json
   8 from datetime import datetime
   9 from multiprocessing import Pool
  10 from itertools import islice
  11 from helper import find_dumps, open_fileset
  12 import pandas as pd
  13 import pyarrow as pa
  14 import pyarrow.parquet as pq
  15
  16
  17 def parse_submission(post, names = None):
  18     if names is None:
  19         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']
  20
  21     try:
  22         post = json.loads(post)
  23     except (json.decoder.JSONDecodeError, UnicodeDecodeError) as e:
  24         #        print(e)
  25         #        print(post)
  26         row = [None for _ in names]
  27         row[-1] = "json.decoder.JSONDecodeError|{0}|{1}".format(e,post)
  28         return tuple(row)
  29
  30     row = []
  31
  32     for name in names:
  33         if name == 'created_utc' or name == 'retrieved_on':
  34             val = post.get(name,None)
  35             if val is not None:
  36                 row.append(datetime.fromtimestamp(int(post[name]),tz=None))
  37             else:
  38                 row.append(None)
  39         elif name == 'edited':
  40             val = post[name]
  41             if type(val) == bool:
  42                 row.append(val)
  43                 row.append(None)
  44             else:
  45                 row.append(True)
  46                 row.append(datetime.fromtimestamp(int(val),tz=None))
  47         elif name == "time_edited":
  48             continue
  49         elif name == 'has_media':
  50             row.append(post.get('media',None) is not None)
  51
  52         elif name not in post:
  53             row.append(None)
  54         else:
  55             row.append(post[name])
  56     return tuple(row)
  57
  58 dumpdir = "/gscratch/comdata/raw_data/reddit_dumps/submissions"
  59
  60 files = list(find_dumps(dumpdir))
  61
  62 pool = Pool(28)
  63
  64 stream = open_fileset(files)
  65
  66 N = 100000
  67
  68 rows = pool.imap_unordered(parse_submission, stream, chunksize=int(N/28))
  69
  70 schema = pa.schema([
  71     pa.field('id', pa.string(),nullable=True),
  72     pa.field('author', pa.string(),nullable=True),
  73     pa.field('subreddit', pa.string(),nullable=True),
  74     pa.field('title', pa.string(),nullable=True),
  75     pa.field('created_utc', pa.timestamp('ms'),nullable=True),
  76     pa.field('permalink', pa.string(),nullable=True),
  77     pa.field('url', pa.string(),nullable=True),
  78     pa.field('domain', pa.string(),nullable=True),
  79     pa.field('score', pa.int64(),nullable=True),
  80     pa.field('ups', pa.int64(),nullable=True),
  81     pa.field('downs', pa.int64(),nullable=True),
  82     pa.field('over_18', pa.bool_(),nullable=True),
  83     pa.field('has_media',pa.bool_(),nullable=True),
  84     pa.field('selftext',pa.string(),nullable=True),
  85     pa.field('retrieved_on', pa.timestamp('ms'),nullable=True),
  86     pa.field('num_comments', pa.int64(),nullable=True),
  87     pa.field('gilded',pa.int64(),nullable=True),
  88     pa.field('edited',pa.bool_(),nullable=True),
  89     pa.field('time_edited',pa.timestamp('ms'),nullable=True),
  90     pa.field('subreddit_type',pa.string(),nullable=True),
  91     pa.field('subreddit_id',pa.string(),nullable=True),
  92     pa.field('subreddit_subscribers',pa.int64(),nullable=True),
  93     pa.field('name',pa.string(),nullable=True),
  94     pa.field('is_self',pa.bool_(),nullable=True),
  95     pa.field('stickied',pa.bool_(),nullable=True),
  96     pa.field('quarantine',pa.bool_(),nullable=True),
  97     pa.field('error',pa.string(),nullable=True)])
  98
  99 with  pq.ParquetWriter("/gscratch/comdata/output/reddit_submissions.parquet_temp",schema=schema,compression='snappy',flavor='spark') as writer:
 100     while True:
 101         chunk = islice(rows,N)
 102         pddf = pd.DataFrame(chunk, columns=schema.names)
 103         table = pa.Table.from_pandas(pddf,schema=schema)
 104         if table.shape[0] == 0:
 105             break
 106         writer.write_table(table)
 107
 108     writer.close()
 109