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Python 3 like CSV module for Python 2

Project description

csv342
======

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) 2016-2018, Thomas Aglassinger
All rights reserved.

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


Version history
---------------

Version 1.0.0, 2018-04-02
* Fixed ``DictReader`` so that it can now read from a list of lines
(`issue #1 <https://github.com/roskakori/csv342/issues/1>`_, contributed by
Lucas Wiman).
* Fixed ``AttributeError`` in ``StringIO`` test (contributed by Lucas Wiman).

Version 0.2, 2016-04-17
* Fixed version number when running under Python 3.
* Fixed helper constant ``IS_PYHTON2`` which always was ``False``.
* Added remaining symbols from Python 2's ``csv`` module.

Version 0.1, 2016-04-16
* Initial release.

Project details


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