+++ /dev/null
-import pyarrow.dataset as ds
-from itertools import groupby
-
-# A pyarrow dataset abstracts reading, writing, or filtering a parquet file. It does not read dataa into memory.
-
-dataset = ds.dataset('/gscratch/comdata/output/reddit_submissions_by_author.parquet', format='parquet')
-
-# let's get all the comments to two subreddits:
-subreddits_to_pull = ['seattlewa','seattle']
-
-# instead of loading the data into a pandas dataframe all at once we can stream it.
-scan_tasks = dataset.scan(filter = ds.field('subreddit').isin(subreddits_to_pull), columns=['id','subreddit','CreatedAt','author','ups','downs','score','subreddit_id','stickied','title','url','is_self','selftext'])
-
-# simple function to execute scantasks and generate rows
-def iterate_rows(scan_tasks):
- for st in scan_tasks:
- for rb in st.execute():
- df = rb.to_pandas()
- for t in df.itertuples():
- yield t
-
-row_iter = iterate_rows(scan_tasks)
-
-# now we can use python's groupby function to read one author at a time
-# note that the same author can appear more than once since the record batches may not be in the correct order.
-author_submissions = groupby(row_iter, lambda row: row.author)
-
-count_dict = {}
-
-for auth, posts in author_submissions:
- if auth in count_dict:
- count_dict[auth] = count_dict[auth] + 1
- else:
- count_dict[auth] = 1
-
-# since it's partitioned and sorted by author, we get one group for each author
-any([ v != 1 for k,v in count_dict.items()])
-