style - analyse surface characteristics of a document
] [-l length
] [--print-ari ari
analyses the surface characteristics of the writing style of a
document. It prints various readability grades, length of words, sentences and
paragraphs. It can further locate sentences with certain characteristics. If
no files are given, the document is read from standard input.
Numbers are counted as words with one syllable. A sentence is a sequence of
words, that starts with a capitalised word and ends with a full stop, double
colon, question mark or exclamation mark. A single letter followed by a dot is
considered an abbreviation, so it does not end a sentence. Various
multi-letter abbreviations are recognized, they do not end a sentence as well.
A paragraph consists of two or more new line characters.
understands cpp(1) #line
lines for being able to give
precise locations when printing sentences.
- Kincaid formula
- The Kincaid Formula was developed for U.S. Navy training
manuals; it ranges in difficulty from 5.5 to 16.3. It is probably best
applied to technical documents, because it is based on adult training
manuals rather than school book text. Dialogs (often found in fictional
texts) are usually a series of short sentences, which lowers the score. On
the other hand, scientific texts with many long scientific terms are rated
higher, although they are not necessarily harder to read for people who
are familiar with those terms.
Kincaid = 11.8*syllables/wds+0.39*wds/sentences-15.59
- Automated Readability Index
- The Automated Readability Index is typically higher than
Kincaid and Coleman-Liau, but lower than Flesch.
ARI = 4.71*chars/wds+0.5*wds/sentences-21.43
- Coleman-Liau Formula
- The Coleman-Liau Formula usually gives a lower grade than
Kincaid, ARI and Flesch when applied to technical documents.
Coleman-Liau = 5.89*chars/wds-0.3*sentences/(100*wds)-15.8
- Flesch Reading Ease formula
- Developed by Rudolph Flesch in 1948, the Flesch Reading
Ease formula is based on school texts covering grades 3 to 12. It is
widespread, especially in the USA, because it is computed easily and
produces good results. The index ranges from 0 (hard) to 100 (easy).
Standard English documents average around 60 to 70. Applying it to German
documents gives bad results because of the different language structure.
Flesch Index = 206.835-84.6*syll/wds-1.015*wds/sent
- Fog Index
- The Fog index was developed by Robert Gunning. Its value is
a school grade. The “ideal” Fog Index level is 7 or 8. A level
above 12 indicates the writing sample is too hard for most people to read.
Texts less than 100 words will not produce meaningful results. Note that a
correct implementation would not count words of three or more syllables
that are proper names, combinations of easy words, or made three syllables
by suffixes such as –ed, –es, or –ing.
Fog Index = 0.4*(wds/sent+100*((wds >= 3 syll)/wds))
- Lix formula
- The Lix formula developed by Björnsson from Sweden is
very simple and employs a mapping table as well:
Lix = wds/sent+100*(wds >= 6 char)/wds
- SMOG Grading
- The SMOG Grading for English texts was developed by
McLaughlin in 1969. Its result is a school grade.
SMOG Grading = square root of (((wds >= 3 syll)/sent)*30) + 3
It was adapted to German by Bamberger and Vanecek in 1984, who changed the
constant +3 to -2.
The word usage counts are intended to help identify excessive use of particular
parts of speech.
- Verb Phrases
- The category of verbs labeled "to be" identifies
phrases using the passive voice. Use the passive voice sparingly, in favor
of more direct verb forms. The flag -p causes style to list
all occurrences of the passive voice.
The verb category "aux" measures the use of modal auxiliary verbs,
such as "can", "could", and "should". Modal
auxiliary verbs modify the mood of a verb.
- The conjunctions counted by style are coordinating and
subordinating. Coordinating conjunctions join grammatically equal sentence
fragments, such as a noun with a noun, a phrase with a phrase, or a clause
to a clause. Coordinating conjunctions are "and,"
"but," "or," "yet," and
Subordinating conjunctions connect clauses of unequal status. A subordinating
conjunction links a subordinate clause, which is unable to stand alone, to an
independent clause. Examples of subordinating conjunctions are
"because," "although," and "even if."
- Pronouns are contextual references to nouns and noun
phrases. Documents with few pronouns generally lack cohesiveness and
fluidity. Too many pronouns may indicate ambiguity.
- Nominalizations are verbs that are changed to nouns. Style
recognizes words that end in "ment," "ance,"
"ence," or "ion" as nominalizations. Examples are
"endowment," "admittance," and
"nominalization." Too much nominalization in a document can
sound abstract and be difficult to understand. The flag -N causes
style to list all nominalizations. The flag -n prints all
sentences with either the passive voice or a nominalization.
- -L language, --language
- set the document language.
- -l length, --print-long
- print all sentences longer than length words.
- -r ari, --print-ari ari
- print all sentences whose readability index (ARI) is
greater than ari.
- -p passive, --print-passive
- print all sentences phrased in the passive voice.
- -N nominalizations, --print-nom
- print all sentences containing nominalizations.
- -n nominalizations-passive,
- print all sentences phrased in the passive voice or
- -h, --help
- Print a short usage message.
- Print the version.
On usage errors, 1 is returned. Termination caused by lack of memory is
signalled by exit code 2.
- specifies the document language. The default language is
- specifies the document character set. The default character
set is ASCII.
This program is GNU software, copyright 1997–2005 Michael Haardt
It contains contributions by Jason Petrone <firstname.lastname@example.org> and Uschi
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA.
There has been a style command on old UNIX systems, which is now part of the
AT&T DWB package. The original version was bound to roff by enforcing a
call to deroff.
Cherry, L.L.; Vesterman, W.: Writing Tools—The STYLE and DICTION
, Computer Science Technical Report 91, Bell Laboratories,
Murray Hill, N.J. (1981), republished as part of the 4.4BSD User's
Supplementary Documents by O'Reilly.