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How to create a frequency list?

Revision as of 14:20, 28 July 2021 by Yug (talk | contribs) (→‎From frequency data to clean list of {item}s)

Words lists sorted by frequency are a very good way to cover one language methodically. After reading this page you will be able to find or create your own frequency list, clean and split it into easy-to-handle files.

Reminder : to start a recording session you need
  1. One LinguaLibre user,
  2. One willing speaker, and
  3. One list of items to record with one item by line.
    One item can be any easy to read sign, word, sentence or paragraph. The most common use-case is to record a comprehensive words list for your target language.

Reusing open license frequency lists

Hermite Dave's lists

Hermite Dave created 61 frequency lists from OpenSubtitle data, covering most major languages under CC license. This data requires minor clean up, example with Korean (ko) : 

mkdir -p ./clean                                                              # create a folder
google-chrome github.com/hermitdave/FrequencyWords/tree/master/content/2018   # open in web-browse to browse available languages
iso=ko                                                                        # defined your target language
curl https://raw.githubusercontent.com/hermitdave/FrequencyWords/master/content/2018/${iso}/${iso}_50k.txt | sort -k 2,2 -n -r | cut -d' ' -f1 | sed -E 's/^/# /g' > ./clean/${iso}-all.txt
# download, sort by 2nd column numerical value descendant, cut by space then keep first field, add # to make a list, print all to file.
split -d -l 5000  --additional-suffix=".txt" ./clean/${iso}-all.txt ./clean/${iso}-words-by-frequency-
# split in files of 5000 items

On LinguaLibre.org, create your lists as List:{Iso3}/words-by-frequency-00001-to-5000, etc. Ex. List:Pol/words-by-frequency-00001-to-02000.

After creating the list on LinguaLibre, add the following to its talkpage: 

==== Source ====
{{Hermite Dave}}

UNILEX's lists

UNILEX is an Unicode Consortium project which curates 999 languages. As many frequency lists are available under GNU-like license. This data requires minor clean up, example with Igbo (ig) : 

mkdir -p ./clean                                                              # create a folder
google-chrome github.com/lingua-libre/unilex/tree/master/data/frequency       # open in web-browse to browse available languages
iso=ig                                                                        # defined your target language
curl https://raw.githubusercontent.com/lingua-libre/unilex/master/data/frequency/${iso}.txt | tail -n +5 | sort -k 2,2 -n -r | cut -d$'\t' -f1 | sed -E 's/^/# /g' > ./clean/${iso}-all.txt
# download, remove first 5 lines, sort by 2nd column numerical value descendant, cut and keep first field, add # to make a list, print all to file.
split -d -l 5000  --additional-suffix=".txt" ./clean/${iso}-all.txt ./clean/${iso}-words-by-frequency-
# split in files of 5000 items

On LinguaLibre.org, create your lists as List:{Iso3}/words-by-frequency-00001-to-5000, etc. Ex. List:Pol/words-by-frequency-00001-to-02000.

After creating the list on LinguaLibre, add the following to its talkpage: 

==== Source ====
{{UNILEX License}}

Subtlex's lists

The Subtlex movement, a group of academic frequency list studies based on open subtitles, also provides about 10 of the highest quality frequency lists. Items are better cleaned up, etc. These resources are published under various licenses. Their usage on LinguaLibre must be on a case by case basis.

Corpus

Requirements for relevant corpus :

  • Size: 2M+ words.
  • Type: raw text.
  • Language: monolingual or close to be.

Download a corpus

You can download available corpuses in your language or collect your own corpus via some datamining. Corpura are easily available for about 60 languages. Corpuses for rare language are likely missing, you will likely have to do some data mining.

Some research centers are curating the web to provide large corpura to linguists and netizens alike.

Wiki(p)edia dumps

One possibility is to harvest Wikipedia's contents. See:

From corpus to frequency data `{occurences} {item}`

Main tools will be grep to grab the text strings, awk to count them, sort to sort and rank them.

Characters frequency (+sorted)

$ grep -o '\S' longtext.txt | awk '{a[$1]++}END{for(k in a)print a[k],k}' | sort -n -r -t' ' -k1,1 > sorted-letters.txt

Space-separated Words frequency (+sorted):

$ grep -o '\w*' longtext.txt | awk '{a[$1]++}END{for(k in a)print a[k],k}' | sort -n -r -t' ' -k1,1  > sorted-words.txt
# or 
$ awk '{a[$1]++}END{for(k in a)print a[k],k}' RS=" |\n" myfile.txt | sort -n -r -t' ' -k1,1 > sorted-words.txt

Loop on all .txt, recursively within folders

find -iname '*.txt' -exec cat {} \; | grep -o '\w*' | awk '{a[$1]++}END{for(k in a)print a[k],k}' | sort -n -r -t' ' -k1,1 > sorted-words.txt

Output

39626 aš
35938 ir
33361 tai
28520 tu'21th
26213 kad'toto
...

Cleaning up frequency lists

Most sources provide wordlists with {number_of_apparitions}{separator}{item} or its mirror {item}{separator}{number_of_apparitions}}, already sorted from most frequent to less ones. We what to keep the field {item}.

Display input we have Display output we want 
$ cat frequency-list.txt
39626 aš
35938 ir
33361 tai
28520 tu'21th
26213 kad'toto
...

$ cat words-list.txt
# aš
# ir
# tai
# tu'21th
# kad'toto
# ...
Command 
cut frequency-list.txt -d$' ' -f2 | sed -E 's/^/# /g' > words-list.txt
# load file line by line, cut by space then keep field 2, replace start of line by # on all lines, print in file.

This final result is what you want for LinguaLibre Help:Create your own lists.

Additional helpers

Sort command

See man sort for details.

-n: numeric sort
-r: reverse (descending)
-t: changes field separator to ' ' character
-k: as -k:1,1, sort key starts on field 1 and ends on field 1

Counting lines of a file

wc -l filename.txt       # -l : lines

See sample of a file

head -n 50 filename.txt       # -n : number of line

Splitting a very long file

split -d -l 2000 --additional-suffix=".txt" YUE-words-by-frequency.txt  YUE-words-by-frequency-

Words-lists files generally are be over 10k lines long, thus not convenient to run recording sessions. Given 1000 recordings per hour via LinguaLibre and 3 hours sessions being quite good and intense, we recommend sub-files of :

  • 1000 lines, so you use 1, 2 or 3 files per session
  • 3000 lines, so you use 1 file per session and kill it off like a warrior ... if your speaker and yourself survives.

See How to split a large text file into smaller files with equal number of lines in terminal?

Convert encoding

iconv -f "GB18030" -t "UTF-8" SUBTLEX-CH-WF.csv -o $iso2-words.txt

Create frequency list from en:Dragon

See also 101 Wikidata/Wikipedia API via JS
curl 'https://en.wikipedia.org/w/api.php?action=query&titles=Dragon&prop=extracts&explaintext&redirects&converttitles&callback=?&format=xml' | tr '\040' '\012' | sort | uniq -c | sort -k 1,1 -n -r > output.txt

How to compare lists ?

[Section status: Draft, to continue.] (example).
 comm - compare two sorted files line by line

See also

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