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basic streaming text processing

Project description

====
pyin
====

It's like sed, but Python!

.. image:: https://travis-ci.org/geowurster/pyin.svg?branch=0.4
:target: https://travis-ci.org/geowurster/pyin

.. image:: https://coveralls.io/repos/geowurster/pyin/badge.svg?branch=master
:target: https://coveralls.io/r/geowurster/pyin?branch=master


Examples
========

See the `Cookbook <https://github.com/geowurster/pyin/blob/master/Cookbook.rst>` for more examples.

Change newline character in a CSV.

.. code-block:: console

$ more sample-data/csv-with-header.csv | pyin "line.replace('\n', '\r\n')" > output.csv

Extract a BigQuery schema from an existing table and pretty print it:

.. code-block:: console
$ bq show --format=json ${DATASET}.${TABLE} | pyin -m json -m pprint "pprint.pformat(json.loads(line)['schema']['fields'])"
[{u'mode': u'NULLABLE', u'name': u'mmsi', u'type': u'STRING'},
{u'mode': u'NULLABLE', u'name': u'longitude', u'type': u'FLOAT'},
{u'mode': u'NULLABLE', u'name': u'latitude', u'type': u'FLOAT'}
...]

Read the first 100K lines of a CSV and write only the lines where column
'Msg type' is equal to 5.

.. code-block:: console

$ pyin -i ${INFILE} -o ${OUTFILE} \
--true \
--lines 100000 \
--reader csv.DictReader \
--import csv \
--import newlinejson \
--writer newlinejson.Writer
"line['Msg type'] == '5'"


Installing
==========

Via pip:

$ pip install git+https://github.com/geowurster/pyin.git

From master branch:

$ git clone https://github.com/geowurster/pyin
$ python setup.py install


Gotchas
=======

It's easy to completely modify the line content:

.. code-block:: console

$ pyin -i sample-data/csv-with-header.csv "'operation'"
operationoperationoperationoperationoperationoperation

Forgetting to use ``-t`` to only get lines that evaluate as ``True``:

.. code-block:: console

$ pyin -i LICENSE.txt "'are' in line"
FalseFalseFalseFalseFalseFalseTrueFalseFalseFalseFalseFalseFalseFalseFalseFalseTrueFalseFalseFalseFalseFalseFalseFalseFalseFalseFalseFalse

$ pyin -i LICENSE.txt "'are' in line" -t
modification, are permitted provided that the following conditions are met:
derived from this software without specific prior written permission.

The ``--reader-option key=val`` values are parsed to their Python type but if the user wants to
specify something like which JSON library to use for a ``newlinejson.Reader()``
instance then they must do that via the ``--statement`` option:

.. code-block:: console

$ pyin -i ${INFILE} -o ${OUTFILE}
--true
--import newlinejson \
--import ujson
--reader newlinejson.Reader \
--writer newlinejson.Writer \
--statement "newlinejson.JSON = ujson" \
"'type' in line and line['type'] is 5"


Developing
==========

Install:

.. code-block:: console

$ git clone https://github.com/geowurster/pyin
$ cd pyin
$ virtualenv venv
$ source venv/bin/activate
$ pip install -r requirements-dev.txt
$ pip install -e .
$ nosetests --with-coverage
$ pep8 --max-line-length=120 pyin.py

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