D3.2a: An Afaan Oromo corpus, sized 3 million words

Building the Afaan Oromo Web corpus

We have used the following steps to create a big Oromo Web corpus: First, adopting the Corpus factory method [1] bigrams of Oromo words from the Crúbadán database [2] were used to query Bing search engine for documents in Oromo. URLs of 9,847 documents found by the search engine were used as starting points for web crawler SpiderLing [3].

The following language models were created:

  • Character trigram model for language detection. 372 KB of text from documents found by the search engine and manually checked was used to train the model.
  • Byte trigram model for character encoding detection. The model was trained using web pages obtained by the Corpus factory method.
  • 253 most frequent Oromo words from the manually checked bigrams of words from the Crúbadán database were used as a wordlist to check the language of a running text by boilerplate removal tool jusText [4].

The crawler was set to harvest web domains in national top level domains of Ethiopia, Eritrea, Somalia, Djibouti (et, er, so, dj) and other general TLDs (com, org, net, gov, info, edu). 42 GB of http responses was gathered in the process. HTML tags and boilerplate paragraphs were removed from the raw data by jusText. Oromo texts were separated using the character trigram language model.

Duplicate or near duplicate paragraphs were identified and removed using tool onion [4]. The final size of the corpus is 32 MB and 5.1 million tokens. The corpus is called orWaC16 (Oromo `Web as Corpus' corpus, year 2016).

Corpus properties

Basic properties of corpus sources are summarised below.

The size of corpus structures:

Document count 8,851
Paragraph count 76,115
Sentence count 250,432
Token count 5,091,696
Latin script lexicon size 273,056

Document count – the most frequent web domains and domain size distribution:

Top level domains Web domains Second level domain size distribution
org 5,676 * 2,695 At least 1000 documents 2
com 2,054 1,010 At least 500 documents 4
net 839 632 At least 100 documents 16
et 213|com 518 At least 50 documents 21
* 438 At least 10 documents 45 304 At least 5 documents 60 291 At least 1 document 190
* 287 276

The content of news/politics and religious sites has a significant presence in the corpus sources.

The most frequent words:

Word (Latin script) Count
akka 82,032
kan 71,775
hin 65,390
fi 64,710
Oromoo 32,189
kana 26,818
tokko 26,699
itti 25,926
waan 24,733
yeroo 22,580
keessatti 22,189
isa 21,732
isaa 21,636
irratti 20,666
jiru 20,655

Corpus query interface

The corpus has been indexed by corpus manager and query system Sketch Engine [5]. The corpus can be searched at


  • [1] -- Kilgarriff, Adam, Siva Reddy, Jan Pomikálek, and P. V. S. Avinesh. "A Corpus Factory for Many Languages." In LREC. 2010.
  • [2] -- Scannell, Kevin P. "The Crúbadán Project: Corpus building for under-resourced languages." In Building and Exploring Web Corpora: Proceedings of the 3rd Web as Corpus Workshop, vol. 4, pp. 5-15. 2007.
  • [3] -- Suchomel, Vít, and Jan Pomikálek. "Efficient web crawling for large text corpora." In Proceedings of the seventh Web as Corpus Workshop (WAC7), pp. 39-43. 2012.
  • [4] -- Pomikálek, Jan. "Removing boilerplate and duplicate content from web corpora." Disertační práce, Masarykova univerzita, Fakulta informatiky (2011).
  • [5] -- Kilgarriff, Adam, Vít Baisa, Jan Bušta, Miloš Jakubíček, Vojtěch Kovář, Jan Michelfeit, Pavel Rychlý, and Vít Suchomel. "The Sketch Engine: ten years on." Lexicography 1, no. 1 (2014): 7-36.
Last modified 5 months ago Last modified on 01/17/17 12:42:34