I have a hacky way of achieving this using boto3
(1.4.4), pyarrow
(0.4.1) and pandas
(0.20.3).
First, I can read a single parquet file locally like this:
import pyarrow.parquet as pq path = 'parquet/part-r-00000-1e638be4-e31f-498a-a359-47d017a0059c.gz.parquet' table = pq.read_table(path) df = table.to_pandas()
I can also read a directory of parquet files locally like this:
import pyarrow.parquet as pq dataset = pq.ParquetDataset('parquet/') table = dataset.read() df = table.to_pandas()
Both work like a charm. Now I want to achieve the same remotely with files stored in a S3 bucket. I was hoping that something like this would work:
dataset = pq.ParquetDataset('s3n://dsn/to/my/bucket')
But it does not:
OSError: Passed non-file path: s3n://dsn/to/my/bucket
After reading pyarrow’s documentation thoroughly, this does not seem possible at the moment. So I came out with the following solution:
Reading a single file from S3 and getting a pandas dataframe:
import io import boto3 import pyarrow.parquet as pq buffer = io.BytesIO() s3 = boto3.resource('s3') s3_object = s3.Object('bucket-name', 'key/to/parquet/file.gz.parquet') s3_object.download_fileobj(buffer) table = pq.read_table(buffer) df = table.to_pandas()
And here my hacky, not-so-optimized, solution to create a pandas dataframe from a S3 folder path:
import io import boto3 import pandas as pd import pyarrow.parquet as pq bucket_name = 'bucket-name' def download_s3_parquet_file(s3, bucket, key): buffer = io.BytesIO() s3.Object(bucket, key).download_fileobj(buffer) return buffer client = boto3.client('s3') s3 = boto3.resource('s3') objects_dict = client.list_objects_v2(Bucket=bucket_name, Prefix='my/folder/prefix') s3_keys = [item['Key'] for item in objects_dict['Contents'] if item['Key'].endswith('.parquet')] buffers = [download_s3_parquet_file(s3, bucket_name, key) for key in s3_keys] dfs = [pq.read_table(buffer).to_pandas() for buffer in buffers] df = pd.concat(dfs, ignore_index=True)
Is there a better way to achieve this? Maybe some kind of connector for pandas using pyarrow? I would like to avoid using pyspark
, but if there is no other solution, then I would take it.
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Answer
You should use the s3fs
module as proposed by yjk21. However as result of calling ParquetDataset you’ll get a pyarrow.parquet.ParquetDataset object. To get the Pandas DataFrame you’ll rather want to apply .read_pandas().to_pandas()
to it:
import pyarrow.parquet as pq import s3fs s3 = s3fs.S3FileSystem() pandas_dataframe = pq.ParquetDataset('s3://your-bucket/', filesystem=s3).read_pandas().to_pandas()