How to use pywws in another language


Some parts of pywws can be configured to use your local language instead of British English. This requires an appropriate language file which contains translations of the various strings used in pywws. The pywws project relies on users to provide these translations.

The pywws documentation can also be translated into other languages. This is a lot more work, but could be very useful to potential users who do not read English very well.

Using existing language files

Program strings

There may already be a pywws translation for your preferred language. First you need to choose the appropriate two-letter code from the list at For example, fr is the code for French. Now use the pywws.localisation module to do a quick test:

python -m pywws.localisation -t fr

This should produce output something like this:

Locale changed from (None, None) to ('fr_FR', 'UTF-8')
Translation set OK
  decimal point: 23,2
  date & time: lundi, 17 décembre (17/12/2012 16:00:48)
  'NNW' => 'NNO'
  'rising very rapidly' => 'en hausse très rapide'
  'Rain at times, very unsettled' => 'Quelques précipitations, très perturbé'

This shows that pywws is already able to generate French output, and that your installation is correctly configured. Now you can edit the language entry in your weather.ini file to use your language code.

If the above test shows no translations into your language then you need to create a new language file, as described below.

Text encodings

The pywws default text encoding is ISO-8859-1, also known as Latin-1. This is suitable for several western European languages but not for some others. If you encounter problems you may need to use a different encoding. See the documentation of pywws.template and pywws.plot for more details.


If you have downloaded the pywws source files, or cloned the GitHub repository (see how to get started with pywws), you can compile a non-English copy of the documentation. This requires the Sphinx package, see dependencies.

First delete the old documentation (if it exists) and then recompile using your language:

cd ~/weather/pywws
rm -rf doc
LANG=fr python -B build_sphinx

Note that the build_sphinx command doesn’t have a --locale (or -l) option, so the language is set by a temporary environment variable.

You can view the translated documentation by using a web browser to read the file ~/weather/pywws/doc/html/index.html.

Writing new language files

There are two ways to write new language files (or update existing ones) – use the Transifex online system or use local files. Transifex is preferred as it allows several people to work on the same language, and makes your work instantly available to others.

To test your translation you will need to have downloaded the pywws source files, or cloned the GitHub repository (see how to get started with pywws). You will also need to install the Babel package, see dependencies.

Using Transifex

If you’d like to use Transifex, please go to the pywws Transifex project, click on “help translate pywws” and create a free account.

Visit the pywws project page on Transifex and click on your language, then click on the “resource” you want to translate. (pywws contains the program strings used when running pywws, the others contain strings from the pywws documentation.) This opens a dialog where you can choose to translate the strings online. Please read Notes for translators before you start.

When you have finished translating you should use the transifex-client program (see dependencies) to download files for testing. For example, this command downloads any updated files for the French language:

cd ~/weather/pywws
tx pull -l fr

Now you are ready to Test the pywws translations.

Using local files

If you prefer not to use the Transifex web site you can edit language files on your own computer. This is done in two stages, as follows.

Extract source strings

Program messages are extracted using the Babel package:

cd ~/weather/pywws
mkdir -p build/gettext
python -B extract_messages

This creates the file build/gettext/pywws.pot. This is a “portable object template” file that contains the English language strings to be translated.

The documentation strings are extracted using the Sphinx package:

cd ~/weather/pywws
python -B extract_messages_doc

This creates several .pot files in the build/gettext/ directory.

Create language files

The sphinx-intl command is used to convert the .pot files to language specific .po files:

cd ~/weather/pywws
sphinx-intl update --locale-dir src/pywws/lang -p build/gettext -l fr

Now you can open the .po files in src/pywws/lang/fr/LC_MESSAGES/ with your favourite text editor and start filling in the empty msgstr strings with your translation of the corresponding msgid string. Please read Notes for translators before you start.

Test the pywws translations

The Babel package is used to compile program strings:

python -B compile_catalog --locale fr

(Replace fr with the code for the language you are testing.)

After compilation you can test the translation:

python build
sudo python install
python -m pywws.Localisation -t fr

Sphinx is used to build the translated documentation:

cd ~/weather/pywws
rm -rf doc
LANG=fr python -B build_sphinx

You can view the translated documentation by using a web browser to read the file ~/weather/pywws/doc/html/index.html.

Notes for translators

The pywws program strings (pywws.po) are quite simple. They comprise simple weather forecasts (“Fine weather”), air pressure changes (“rising quickly”) and the 16 points of the compass (“NNE”). Leave the “(%Z)” in “Time (%Z)” unchanged and make sure your translation’s punctuation matches the original.

The other files contain strings from the pywws documentation. These are in reStructuredText. This is mostly plain text, but uses characters such as backquotes (`), colons (:) and asterisks (*) for special purposes. You need to take care to preserve this special punctuation. Do not translate program source, computer instructions and cross-references like these:

`pip <>`_
:obj:`ParamStore <pywws.DataStore.ParamStore>`\\ (root_dir, file_name)

Translating all of the pywws documentation is a lot of work. However, when the documentation is “compiled” any untranslated strings revert to their English original. This means that a partial translation could still be useful – I suggest starting with the documentation front page, index.po.

Send Jim the translation

I’m sure you would like others to benefit from the work you’ve done in translating pywws. If you’ve been using Transifex then please send me an email ( to let me know there’s a new translation available. Otherwise, please email me any .po files you create.

Comments or questions? Please subscribe to the pywws mailing list and let us know.