提问者:小点点

如何在python中使用py箭头从S3读取分区的拼花文件


我正在寻找使用python从s3的多个分区目录中读取数据的方法。

data_folder/serial_number=1/cur_date=20-12-2012/abcdsd0324324. snappy.parquedata_folder/serial_number=2/cur_date=27-12-2012/asdsdfsd0324324.snappy.parque

pyarrow的ParquetDataset模块具有从分区读取的能力。所以我尝试了以下代码:

>>> import pandas as pd
>>> import pyarrow.parquet as pq
>>> import s3fs
>>> a = "s3://my_bucker/path/to/data_folder/"
>>> dataset = pq.ParquetDataset(a)

它引发了以下错误:

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/

基于pyarrow的留档,我尝试使用s3fs作为文件系统,即:

>>> dataset = pq.ParquetDataset(a,filesystem=s3fs)

这会引发以下错误:

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'

我仅限于使用ECS集群,因此火花/pyspark不是一个选项。

有没有一种方法可以让我们很容易地从s3中的分区目录中轻松读取parket文件?我觉得列出所有目录然后阅读不是这个链接中建议的好做法。我需要将读取的数据转换为熊猫数据帧进行进一步处理


共3个答案

匿名用户

我设法让这个和最新的快速拼花一起工作

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()

感谢Martin通过我们的谈话为我指明了正确的方向

NB:基于基准测试,这将比使用pyarrow慢。一旦通过ARROW-1213在pyarrow中实现s3fs支持,我将更新我的答案

我做了一个快速的基准测试在单独的迭代与pyarrow

代码

>>> 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

更新2019

所有PR之后,Arrow-2038等问题

使用Pyarrow读取镶木地板文件

# 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() 

使用快速镶木地板读取镶木地板文件

# 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()

快速基准

这可能不是最好的基准测试方法。请阅读博客文章以获取直通基准测试

#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

进一步阅读关于皮亚罗的速度

参考:

  • 快速拼花
  • s3fs
  • pyarrow
  • 基于讨论的pyarrow箭头代码

匿名用户

对于python 3.6AWS有一个名为aws-data-wrangler的库,它有助于Pandas/S3/Parquet之间的集成

安装do;

pip install awswrangler

要使用awswrangler1. x.x及更高版本从s3读取分区拼花,请执行;

import awswrangler as wr
df = wr.s3.read_parquet(path="s3://my_bucket/path/to/data_folder/", dataset=True)

通过设置dataset=Trueawswrangler需要分区的拼花文件。它将从您在路径中指定的s3键下方的分区中读取所有单独的拼花文件。

匿名用户

对于那些只想读取已分区的镶木地板文件的部分内容的人来说,pyarrow接受键列表以及要读取分区所有部分的部分目录路径。这种方法对于那些以有意义的方式(例如按年份或国家/地区)对镶木地板数据集进行分区的组织特别有用,允许用户指定他们需要的文件部分。从长远来看,这将降低成本,因为在读取数据集时AWS按字节收费。

# Read in user specified partitions of a partitioned parquet file 

import s3fs
import pyarrow.parquet as pq
s3 = s3fs.S3FileSystem()

keys = ['keyname/blah_blah/part-00000-cc2c2113-3985-46ac-9b50-987e9463390e-c000.snappy.parquet'\
         ,'keyname/blah_blah/part-00001-cc2c2113-3985-46ac-9b50-987e9463390e-c000.snappy.parquet'\
         ,'keyname/blah_blah/part-00002-cc2c2113-3985-46ac-9b50-987e9463390e-c000.snappy.parquet'\
         ,'keyname/blah_blah/part-00003-cc2c2113-3985-46ac-9b50-987e9463390e-c000.snappy.parquet']

bucket = 'bucket_yada_yada_yada'

# Add s3 prefix and bucket name to all keys in list
parq_list=[]
for key in keys:
    parq_list.append('s3://'+bucket+'/'+key)

# Create your dataframe
df = pq.ParquetDataset(parq_list, filesystem=s3).read_pandas(columns=['Var1','Var2','Var3']).to_pandas()