Use appropriate readability function depending on the used language.

[SuiOni]

There are readability functions, whom parameters differ depending on the used language.
The Flesh-Readability-Ease is such a language depending function.

It would be useful to automatically the appropriate function for the used language.

Score	Interpretation	Estimated Reading Grade
90 to 100	Very easy	5th grade
80 to 90	Easy	6th grade
70 to 80	Fairly easy	7th grade
60 to 70	Standard	8th and 9th grade
50 to 60	Fairly difficult	10th to 12th grade (high school)
30 to 50	Difficult	College
0 to 30	Very difficult	College graduate

Yoast/YoastSEO.js#267

[bdewilde]

Hi @SuiOni , sounds like a reasonable idea, and shouldn't be too hard to implement.

Since I've never seen language-dependent versions of Flesch Readability Ease, and the link you provided only includes references in German and Russian — neither of which I speak 😖 — I'm not able to access any of the references from the issue you linked to, I don't suppose you could point me to an English- or Spanish-language reference on these different readability formulations?

[SuiOni]

FLE(German) = 180 - ( total words/total sentences ) - 58.5( total syllables/total words ). https://de.wikipedia.org/wiki/Lesbarkeitsindex

FLE(Spanish) = 206.84 - 1.02 ( total words/total sentences ) - 0.60( syllables in 100 words ).

FLE(Italian) = 217 - 1.3( total words/total sentences ) - 0.6( syllables in 100 words ).
https://it.wikipedia.org/wiki/Formula_di_Flesch

FLE(French) = 207 - 1.015( total words/total sentences ) - 73.6( total syllables/total words ).

FLE(Russian) = 206.835 - 1.3( total syllables/total words ) - 60.1( total words/total sentences).
https://ru.wikipedia.org/wiki/%D0%98%D0%BD%D0%B4%D0%B5%D0%BA%D1%81_%D1%83%D0%B4%D0%BE%D0%B1%D0%BE%D1%87%D0%B8%D1%82%D0%B0%D0%B5%D0%BC%D0%BE%D1%81%D1%82%D0%B8

FLE(Dutch) = 206.84 - 0.77( #syllables in 100 words ) - 0.93( total words/total sentences ).
http://essay.utwente.nl/64884/1/Hensel,%20T.N.C.A.%20-%20s0170860%20(verslag).pdf (page 7)

So it's not easy to find real references in English for all languages.
I found Wikipedia sites and some other references.
For Spanish and French, I could not find any references except Yoast/YoastSEO.js#267

[bdewilde]

This is a great start, thanks a ton for your help!

[bdewilde]

Hey again, I'm looking at the link for the Italian formulation, and I think the multiplicative constants are swapped. Shouldn't it be

FLE(Italian) = 217 - 0.6( total words/total sentences ) - 1.3( syllables in 100 words )

?

[SuiOni]

Interesting. According to this paper http://www.rebe.rau.ro/RePEc/rau/jisomg/SP11/JISOM-SP11-A13.pdf page 3, Wikipedia seems to have it wrong.

[bdewilde]

Wow! Thanks for double-checking, I appreciate it.

[bdewilde]

Hi again, I'm going to close this issue out — I'll be merging a PR in shortly with the requested update. 👍

[SuiOni]

Hey my pleasure to help,
Textacy is a really nice library so I'm excited to help out.
Actually, I would like to contribute more as I am also a python developer. But I don't have much experience with open source contribution.
Let me know if there's something I could do.
Cheers Sak