csv342 0.2

Python 3 like CSV module for Python 2

csv342 is a Python module similar to the the csv module in the standard library. Under Python 3, it just calls the standard csv module. Under Python 2, it provides a Python 3 like interface to reading and writing CSV files, in particular concerning non ASCII characters.

It is distributed under the BSD license. The source code is available from https://github.com/roskakori/csv342.

Installation

To install, simply run:

$ pip install --upgrade csv342

Alternatively you can download the distributin archive from http://pypi.python.org/pypi/csv342/, unpack it and copy csv342.py into your application path.

Examples

First, consider changing all string literals in you source code to unicode instead of str under Python 2 using to avoid the messy u string prefix.

>>> from __future__ import unicode_literals

The following examples assume you did that, making your Python 2 code look like Python 3 even more.

Once you import csv342 using

>>> import csv342 as csv

your code can call CSV functions the same way independent of whether it runs under Python 2 or 3. First, let’s write a few test data to a io.StringIO:

>>> import io
>>> csv_stream = io.StringIO()
>>> csv_writer = csv.writer(csv_stream)
>>> csv_writer.writerow(['a', 'b'])
>>> csv_writer.writerow(['1', '"x"'])
>>> csv_content = csv_stream.getvalue()
>>> str(csv_content)
'a,b\r\n1,"""x"""\r\n'

To read data from a io.StringIO use:

>>> csv_stream = io.StringIO('a,b\r\n1,"""x"""\r\n')
>>> csv_reader = csv.reader(csv_stream)
>>> for row in csv_reader:
>>>     print(row)

To read a UTF-8 encoded CSV file with non ASCII characters use:

>>> csv_path = os.path.join('test', 'utf-8.csv')
>>> with io.open(csv_path, encoding='utf-8', newline='') as csv_file:
>>>     csv_reader = csv.reader(csv_file, delimiter=',')
>>>     for row in csv_reader:
>>>         print('row {0:d}: data={1}'.format(csv_reader.line_num, row))

Features

• Supports Python 2’s unicode strings.

• Provides reader, writer, DictReader and DictWriter.

• Supports reading and writing with files, io.StringIO etc.

• Rejects attempts to read or write with cStringIO or StringIO.StringIO (which do not really work with unicode); use io.StringIO instead.

Limitations

• All limitations of the standard csv module apply.

• Uses the standard csv.Sniffer under Python 2.

• Requires Python 2.6 or later.

Performance

Processing a CSV with Python 2 using csv342 is about 30% slower than processing it with Python 3. This is probably due the fact that under Python 2 there is an intermediate translation to UTF-8 using pure Python code while in Python 3 uses mostly native code.

Provided you have both Python 2 and 3 installed on the same machine, you can test this yourself running:

python3 test/performance.py
python2 test/performance.py

On an ancient laptop with a core 2 duo Intel CPU and Ubuntu 14.04, this takes 10.2 seconds respectively 13.6 seconds.

License

Copyright (c) 2016, Thomas Aglassinger All rights reserved.

Distributed under the BSD License. For more information, see LICENSE.txt.

Version history

Version 0.2, 2016-04-17

• Fixed version number when running under Python 3.

• Fixed helper constand IS_PYHTON2 which always was False.

• Added remaining symbols from Python 2’s csv module.

Version 0.1, 2016-04-16

• Initial release.