I looking for ways to read data from multiple partitioned directories from s3 using python.
data_folder/serial_number=1/cur_date=20-12-2012/abcdsd0324324.snappy.parquet data_folder/serial_number=2/cur_date=27-12-2012/asdsdfsd0324324.snappy.parquet
pyarrow's ParquetDataset module has the capabilty to read from partitions. So I have tried the following code :
>>> import pandas as pd
>>> import pyarrow.parquet as pq
>>> import s3fs
>>> a = "s3://my_bucker/path/to/data_folder/"
>>> dataset = pq.ParquetDataset(a)
It threw the following error :
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/my_username/anaconda3/lib/python3.6/site-packages/pyarrow/parquet.py", line 502, in __init__
self.metadata_path) = _make_manifest(path_or_paths, self.fs)
File "/home/my_username/anaconda3/lib/python3.6/site-packages/pyarrow/parquet.py", line 601, in _make_manifest
.format(path))
OSError: Passed non-file path: s3://my_bucker/path/to/data_folder/
Based on documentation of pyarrow I tried using s3fs as the file system, ie :
>>> dataset = pq.ParquetDataset(a,filesystem=s3fs)
Which throws the following error :
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/my_username/anaconda3/lib/python3.6/site-packages/pyarrow/parquet.py", line 502, in __init__
self.metadata_path) = _make_manifest(path_or_paths, self.fs)
File "/home/my_username/anaconda3/lib/python3.6/site-packages/pyarrow/parquet.py", line 583, in _make_manifest
if is_string(path_or_paths) and fs.isdir(path_or_paths):
AttributeError: module 's3fs' has no attribute 'isdir'
I am limited to use a ECS cluster, hence spark/pyspark is not an option.
Is there a way we can easily read the parquet files easily, in python from such partitioned directories in s3 ? I feel that listing the all the directories and then reading the is not a good practise as suggested in this link. I would need to convert the read data to a pandas dataframe for further processing & hence prefer options related to fastparquet or pyarrow. I am open to other options in python as well.
I managed to get this working with the latest release of fastparquet & s3fs. Below is the code for the same:
import s3fs
import fastparquet as fp
s3 = s3fs.S3FileSystem()
fs = s3fs.core.S3FileSystem()
#mybucket/data_folder/serial_number=1/cur_date=20-12-2012/abcdsd0324324.snappy.parquet
s3_path = "mybucket/data_folder/*/*/*.parquet"
all_paths_from_s3 = fs.glob(path=s3_path)
myopen = s3.open
#use s3fs as the filesystem
fp_obj = fp.ParquetFile(all_paths_from_s3,open_with=myopen)
#convert to pandas dataframe
df = fp_obj.to_pandas()
credits to martin for pointing me in the right direction via our conversation
NB : This would be slower than using pyarrow, based on the benchmark . I will update my answer once s3fs support is implemented in pyarrow via ARROW-1213
I did quick benchmark on on indivdual iterations with pyarrow & list of files send as a glob to fastparquet. fastparquet is faster with s3fs vs pyarrow + my hackish code. But I reckon pyarrow +s3fs will be faster once implemented.
The code & benchmarks are below :
>>> def test_pq():
... for current_file in list_parquet_files:
... f = fs.open(current_file)
... df = pq.read_table(f).to_pandas()
... # following code is to extract the serial_number & cur_date values so that we can add them to the dataframe
... #probably not the best way to split :)
... elements_list=current_file.split('/')
... for item in elements_list:
... if item.find(date_partition) != -1:
... current_date = item.split('=')[1]
... elif item.find(dma_partition) != -1:
... current_dma = item.split('=')[1]
... df['serial_number'] = current_dma
... df['cur_date'] = current_date
... list_.append(df)
... frame = pd.concat(list_)
...
>>> timeit.timeit('test_pq()',number =10,globals=globals())
12.078817503992468
>>> def test_fp():
... fp_obj = fp.ParquetFile(all_paths_from_s3,open_with=myopen)
... df = fp_obj.to_pandas()
>>> timeit.timeit('test_fp()',number =10,globals=globals())
2.961556333000317
Update 2019
After all PRs, Issues such as Arrow-2038 & Fast Parquet - PR#182 have been resolved.
Read parquet files using Pyarrow
# pip install pyarrow
# pip install s3fs
>>> import s3fs
>>> import pyarrow.parquet as pq
>>> fs = s3fs.S3FileSystem()
>>> bucket = 'your-bucket-name'
>>> path = 'directory_name' #if its a directory omit the traling /
>>> bucket_uri = f's3://{bucket}/{path}'
's3://your-bucket-name/directory_name'
>>> dataset = pq.ParquetDataset(bucket_uri, filesystem=fs)
>>> table = dataset.read()
>>> df = table.to_pandas()
Read parquet files using Fast parquet
# pip install s3fs
# pip install fastparquet
>>> import s3fs
>>> import fastparquet as fp
>>> bucket = 'your-bucket-name'
>>> path = 'directory_name'
>>> root_dir_path = f'{bucket}/{path}'
# the first two wild card represents the 1st,2nd column partitions columns of your data & so forth
>>> s3_path = f"{root_dir_path}/*/*/*.parquet"
>>> all_paths_from_s3 = fs.glob(path=s3_path)
>>> fp_obj = fp.ParquetFile(all_paths_from_s3,open_with=myopen, root=root_dir_path)
>>> df = fp_obj.to_pandas()
Quick benchmarks
This is probably not the best way to benchmark it. please read the blog post for a through benchmark
#pyarrow
>>> import timeit
>>> def test_pq():
... dataset = pq.ParquetDataset(bucket_uri, filesystem=fs)
... table = dataset.read()
... df = table.to_pandas()
...
>>> timeit.timeit('test_pq()',number =10,globals=globals())
1.2677053569998407
#fastparquet
>>> def test_fp():
... fp_obj = fp.ParquetFile(all_paths_from_s3,open_with=myopen, root=root_dir_path)
... df = fp_obj.to_pandas()
>>> timeit.timeit('test_fp()',number =10,globals=globals())
2.931876824000028
Further reading regarding Pyarrow's speed
Reference :