python-stream

Installation

pip install git+git://github.com/SelfHacked/python-stream.git#egg=python-stream

Usage

Read file from S3

from stream.io.s3 import S3ReadFile
from stream.functions.bytes import un_gzip 

# Read line by line
with S3ReadFile(bucket='bucket', key='path/to/file.txt.gz', lines=True) as s3_file:
    for line in un_gzip(s3_file):
        print(line)

# Read in chunks
with S3ReadFile(bucket='bucket', key='path/to/file.txt.gz', lines=False) as s3_file:
    while chunk := s3_file.read(10):
        print(chunk)

Upload data to S3

S3WriteFile only uses binary data. Text data should be converted via an encoder before passing to S3WriteFile write methods.

from stream.io.s3 import S3ReadFile
from stream.io.s3 import S3WriteFile

# write data to s3 file.
with S3WriteFile(bucket='bucket', key='path/to/file.txt.gz') as s3_file:
    s3_file.write(b'test\n')
    s3_file.writelines([b'line 1\n', b'line 2\n'])

# read from the s3 file.    
with S3ReadFile(bucket='bucket', key='path/to/file.txt.gz', lines=True) as s3_file:
    for line in s3_file:
        print(line)

Encoding and Decoding

from stream.functions.bytes import encode, decode

text = [f'line {i}' for i in range(0, 10)]

print('Encoded')
encoded = encode(text)
for line in encoded:
    print(f'   {line}')

print('\nDecoded')
decoded = decode(encode(text))
for line in decoded:
    print(f'   {line}')

Example pipeline

import gzip
import csv
from stream.io.s3 import S3ReadFile, S3WriteFile
from stream.functions.bytes import encode, decode

# Read from s3 file
with S3ReadFile(
    'dev-varuna', 'prs/trait1/ss1/data_head.tsv.gz', lines=False,
) as s3_file, gzip.open(
    s3_file, 'rb',
) as gzip_in:
    # decode
    decode_in = decode(gzip_in)
    
    # parse the csv row
    csv_in = csv.reader(decode_in, delimiter='\t')

    # process step (process step should be in iterable format)
    process = ((line[14], line[12], line[13]) for line in csv_in)
    
    # create tsv lines using a generator
    csv_out = ('\t'.join(line) for line in process)
    
    # add new line
    text_out = (f'{line}\n' for line in csv_out)
    
    # encode text lines into bytes
    encode_out = encode(text_out)
    
    # Write to S3
    with S3WriteFile(
        'dev-varuna', 'prs/trait1/ss1/snps_custom.tsv.gz',
    ) as s3_writer, gzip.open(
        s3_writer, 'wb',
    ) as gzip_out:
        gzip_out.writelines(encode_out)