Global Voices is a community of bloggers and citizen journalists writing and translating news articles in several languages. We crawl articles from this website to create parallel corpora for low-resource languages.

Python 2.7 is required. Install dependencies with:

pip install -r requirements.txt

We can obtain seed URLs from the RSS feeds. It is recommended to add more seeds at different starting dates if starting to crawl from scratch. The crawler will follow the previous and next article links on each page.

For example, to crawl the Malagasy version of the website, run:

mkdir crawl-mg
curl http://mg.globalvoicesonline.org/feed/ | python gv-crawl/make_seeds.py > crawl-mg/seeds.txt
python gv-crawl/crawler.py crawl-mg/seeds.txt crawl-mg --delay 1 2> crawl-mg/crawl.log

The crawling can be interrupted and restarted; it should resume operation automatically. This also makes incremental crawling possible.

Compressed WARC files containing the crawled pages are created.

After we have crawled several versions of the website, we can find parallel documents for a pair of languages. Fist, we insert all articles in a database (repeat for all languages):

python gv-crawl/warc2db.py ./crawl-mg/scrapy.*.warc.gz articles.db

Then, we use the Gargantua sentence aligner to align the sentences from parallel articles:

python gv-crawl/db2bidoc.py en mg articles.db $GARGANTUA
cd $GARGANTUA && mkdir corpus_data && cd corpus_data && ../src/sentence-aligner

The db2bidoc.py creates the tokenized/untokenized/info files necessary for Gargantua to run in the $GARGANTUA directory. These intermediary files (corpus_data, corpus_to_align, input_documents) can be deleted after the last step has been run.

Finally, an XML file containing the bitext is created:

python gv-crawl/align2xml.py eng mlg\
	$GARGANTUA/corpus_to_align/align_info.txt\
	$GARGANTUA/corpus_data/output_data_aligned > en-mg.xml

This XML file can be processed with the teny tools to produce parallel text files.

Copyright (c) 2013, Victor Chahuneau

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