Creating a "dictionary" from KDE translation files

November 1, 2009, [MD]

I've previously written about how I used interwiki links in Wikipedia to extract dictionary information (here and here). After talking with a friend, I got another idea for how I could extract even more dictionary information - localization files. You might know that open source projects like KDE are available in many different languages, translated by (usually) volunteers. In order to make translation easy, and enable volunteers who might not know anything about programming to help out, the text strings to be translated are extracted from the source code, and translated in separate files, often using a library called gettext.

Given that there are these large databases of strings translated into different languages out there, I wondered if I could use that as an addition to a dictionary. I am pretty sure I am not the first to have this idea, in fact, I seem to remember some website where you could search translation strings, but I don't remember where I found that. Anyway, I decided to give it a try.

First I had to find the files. I began by downloading some Debian localization packages, but then remembered that in the finished product, the files (with .mo extension) have been "compiled", so that the program can access them more rapidly, and are not plain text anymore. There might be tools that can extract the strings from the .mo files, but it's much easier to go straight to the "source", and get the localization projects from the SVN repository.

KDE has very nice and helpful pages for their translation teams, for example the page for simplified Chinese tells me clearly how I should go about to download this project, simply enter the command:

svn co svn:// trunk/l10n-kde4/zh_CN/messages

and a bit over a thousand files will be downloaded, with names like koffice/kivio.po. After some initial metadata, these files look like this:

#: rc.cpp:28 msgctxt "Stencils" msgid "Assorted" msgstr "杂类"

#: rc.cpp:29 msgctxt "Stencils" msgid "Electric" msgstr "电子"

#: rc.cpp:30 msgctxt "Stencils" msgid "Network" msgstr "网络"

There is some metadata about where in the code this string comes from, then the key string in English, which will be the same in all translation projects, and then the translation into Chinese. If all we wanted was an English-Chinese dictionary, it would be quite easy to run some regexps to compile this data. However, we would like to make a dictionary of for example Norwegian and Chinese. The corresponding Norwegian file looks like this:

#: rc.cpp:28 msgctxt "Stencils" msgid "Assorted" msgstr "Diverse"

#: rc.cpp:29 msgctxt "Stencils" msgid "Electric" msgstr "Elektrisk"

#: rc.cpp:30 msgctxt "Stencils" msgid "Network" msgstr "Nettverk"

So I wrote a simple program that takes two paths, and opens every file in those two paths, and you can download that script here. If you download the Chinese files into a directory called zh, and the Norwegian files into a directory called no, you can run the program like this:

ruby extract.rb no/messages zh/messages >

and you get a file containing more than a 100,000 lines like this:

Lydstyrke 音量 Tone inn/ut-kurve 曲线淡出 Tone til volum 淡出到音量 Tonetid 淡出时间 Start toning 开始淡出

...which is what we were looking for. You can then easily grep this file to find words you are looking for - many of which won't be in normal dictionaries (especially not Chinese-Norwegian or Esperanto-Urdu or whatever interesting combinations you cook up).

This script can be used for any language combinations, with one caveat. Right now, it is hardcoded to only accept entries that contain at least one Chinese character from the second file, because there is now point to get an entry telling you that XML in Norwegian is XML in Chinese. I do that by adding this:

trans[0][0] =~ /[⾰-⾿]/

which is a regular expression that checks for the existence of Chinese characters. You'd want to remove that, if you were not using it with Chinese.

Stian PS: I realize that calling this a "dictionary" is perhaps not very accurate, they are collocated sentences, not words. However, if the target language is a language that you speak a bit of, you can very often easily isolate the word you are looking for.

Stian Håklev November 1, 2009 Toronto, Canada
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