The MEDLINE N-gram Set

The MEDLINE N-gram Set 2019: by Split, Group, Filter, and Combine Algorithm

The MEDLINE n-gram set (generated by split, group, filter, and combine algorithm) is listed as bellows. For each MEDLINE record, title and abstract are used as the source of n-grams. They are combined, tokenized into sentences, and then tokenized into tokens (words use space as word boundary). Finally, n-grams are generated by filtering out terms with more than 50 characters or the total word count is less than 30. The specifications of generating these n-grams are listed as follows:

• MEDLINE: 2019 - TI and AB (from MEDLINE Baseline Repository - MBR, pubmed19nXXXX.xml -> PmidTiAbS19nXXXX.txt: 1 ~ 972)
• Method: Split, Combine, Filter Algorithm
• Max. Character Size: 50
• Min. word count: 30
• Min. document count: 1

• Total document count: 29,138,919
• Total sentence count: 185,619,887
• Total token count: 3,824,268,997

• N-gram files
  • File format - 3 fields:

    Document count

    Word count

    N-gram

  • Sorted by document count, word count, then alphabetic order of n-grams. N-gram set is not sorted. It can be sorted by nGramUtil package.

• Download:

  N-grams	File	Zip Size	Actual Size	No. of n-grams
  Unigrams	1-gram.2019.tgz	7.2 MB	18 MB	1,075,227
  Bigrams	2-gram.2019.tgz	46 MB	135 MB	6,336,698
  Trigrams	3-gram.2019.tgz	71 MB	233 MB	9,078,536
  Four-grams	4-gram.2019.tgz	50 MB	174 MB	5,729,590
  Five-grams	5-gram.2019.tgz	24 MB	86 MB	2,446,765
  N-gram Set	nGramSet.2019.30.tgz	196 MB	644 MB	24,666,816
  Distilled N-gram Set	distilledNGram.2019.tgz	77 MB	250 MB	9,595,606