text-readability

npm package to calculate statistics from text to determine readability, complexity and grade level of a particular corpus.

A rewrite of textstat library in JS

Usage

install required packages with npm install text-readability

>>> import rs from 'text-readability';

>>> const testData = `
      Playing games has always been thought to be important to 
      the development of well-balanced and creative children; 
      however, what part, if any, they should play in the lives 
      of adults has never been researched that deeply. I believe 
      that playing games is every bit as important for adults 
      as for children. Not only is taking time out to play games 
      with our children and other adults valuable to building 
      interpersonal relationships but is also a wonderful way 
      to release built up tension. `

>>> rs.fleschReadingEase(testData)
>>> rs.fleschKincaidGrade(testData)
>>> rs.colemanLiauIndex(testData)
>>> rs.automatedReadabilityIndex(testData)
>>> rs.daleChallReadabilityScore(testData)
>>> rs.difficultWords(testData)
>>> rs.linsearWriteFormula(testData)
>>> rs.gunningFog(testData)
>>> rs.textStandard(testData)

The argument (text) for all the defined functions remains the same - i.e the text for which statistics need to be calculated.

Install using npm

npm install text-readability

List of Functions

Syllable Count

rs.syllableCount(text, lang='en-US')

Returns the number of syllables present in the given text.

Uses the npm module syllable for syllable calculation. lang currently only used for proper lowercasing
Should be passed to syllable or write own library for this

Lexicon Count

rs.lexiconCount(text, removePunctuation=true)

Calculates the number of words present in the text. Optional removePunctuation specifies whether we need to take punctuation symbols into account while counting lexicons. Default value is true, which removes the punctuation before counting lexicon items.

Sentence Count

rs.sentenceCount(text)

Returns the number of sentences present in the given text.

The Flesch Reading Ease formula

rs.fleschReadingEase(text)

Returns the Flesch Reading Ease Score.

The following table can be helpful to assess the ease of readability in a document.

The table is an example of values. While the maximum score is 121.22, there is no limit on how low the score can be. A negative score is valid.

Score	Difficulty
90-100	Very Easy
80-89	Easy
70-79	Fairly Easy
60-69	Standard
50-59	Fairly Difficult
30-49	Difficult
0-29	Very Confusing

Further reading on Wikipedia

The Flesch-Kincaid Grade Level

rs.fleschKincaidGrade(text)

Returns the Flesch-Kincaid Grade of the given text. This is a grade formula in that a score of 9.3 means that a ninth grader would be able to read the document.

Further reading on Wikipedia

The Fog Scale (Gunning FOG Formula)

rs.gunningFog(text)

Returns the FOG index of the given text. This is a grade formula in that a score of 9.3 means that a ninth grader would be able to read the document.

Further reading on Wikipedia

The SMOG Index

rs.smogIndex(text)

Returns the SMOG index of the given text. This is a grade formula in that a score of 9.3 means that a ninth grader would be able to read the document.

Texts of fewer than 30 sentences are statistically invalid, because the SMOG formula was normed on 30-sentence samples. textstat requires atleast 3 sentences for a result.

Further reading on Wikipedia

Automated Readability Index

rs.automatedReadabilityIndex(text)

Returns the ARI (Automated Readability Index) which outputs a number that approximates the grade level needed to comprehend the text.

For example if the ARI is 6.5, then the grade level to comprehend the text is 6th to 7th grade.

Further reading on Wikipedia

The Coleman-Liau Index

rs.colemanLiauIndex(text)

Returns the grade level of the text using the Coleman-Liau Formula. This is a grade formula in that a score of 9.3 means that a ninth grader would be able to read the document.

Further reading on Wikipedia

Linsear Write Formula

rs.linsearWriteFormula(text)

Returns the grade level using the Linsear Write Formula. This is a grade formula in that a score of 9.3 means that a ninth grader would be able to read the document.

Further reading on Wikipedia

Dale-Chall Readability Score

rs.daleChallReadabilityScore(text)

Different from other tests, since it uses a lookup table of the most commonly used 3000 English words. Thus it returns the grade level using the New Dale-Chall Formula.

Score	Understood by
4.9 or lower	average 4th-grade student or lower
5.0–5.9	average 5th or 6th-grade student
6.0–6.9	average 7th or 8th-grade student
7.0–7.9	average 9th or 10th-grade student
8.0–8.9	average 11th or 12th-grade student
9.0–9.9	average 13th to 15th-grade (college) student

Further reading on Wikipedia

Readability Consensus based upon all the above tests

rs.textStandard(text, float_output=False)

Based upon all the above tests, returns the estimated school grade level required to understand the text.

Optional float_output allows the score to be returned as a float. Defaults to false.