The MEDLINE N-gram Set 2021: 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: 2021 - TI and AB (from MEDLINE Baseline Repository - MBR, pubmed21nXXXX.xml -> PmidTiAbS21nXXXX.txt: 1 ~ 1062)
• Method: Split, Combine, Filter Algorithm
• Max. Character Size: 50
• Min. word count: 30
• Min. document count: 1

• Total document count: 31,850,051
• Total sentence count: 209,685,517
• Total token count: 4,365,354,060

• 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.2021.tgz	8 MB	20 MB	1,185,627
  Bigrams	2-gram.2021.tgz	52 MB	152 MB	7,093,113
  Trigrams	3-gram.2021.tgz	80 MB	265 MB	10,327,977
  Four-grams	4-gram.2021.tgz	58 MB	201 MB	6,620,884
  Five-grams	5-gram.2021.tgz	29 MB	102 MB	2,875,651
  N-gram Set	nGramSet.2021.30.tgz	224 MB	738 MB	28,103,252
  Distilled N-gram Set	distilledNGram.2021.tgz	90 MB	292 MB	11,127,802