GreynirCorrect: Spelling and grammar correction for Icelandic

Overview

GreynirCorrect is a Python 3 (>= 3.8) package and command line tool for checking and correcting spelling and grammar in Icelandic text.

GreynirCorrect relies on the Greynir package, by the same authors, to tokenize and parse text.

GreynirCorrect is documented in detail here.

The software has three main modes of operation, described below.

As a fourth alternative, you can call the JSON REST API of Yfirlestur.is to apply the GreynirCorrect spelling and grammar engine to your text, as documented here.

Token-level correction

GreynirCorrect can tokenize text and return an automatically corrected token stream. This catches token-level errors, such as spelling errors and erroneous phrases, but not grammatical errors. Token-level correction is relatively fast.

Full grammar analysis

GreynirCorrect can analyze text grammatically by attempting to parse it, after token-level correction. The parsing is done according to Greynir's context-free grammar for Icelandic, augmented with additional production rules for common grammatical errors. The analysis returns a set of annotations (errors and suggestions) that apply to spans (consecutive tokens) within sentences in the resulting token list. Full grammar analysis is considerably slower than token-level correction.

Command-line tool

GreynirCorrect can be invoked as a command-line tool to perform token-level correction and, optionally, grammar analysis. The command is correct infile.txt outfile.txt. The command-line tool is further documented below.

Examples

To perform token-level correction from Python code:

>>> from reynir_correct import tokenize
>>> g = tokenize("Af gefnu tilefni fékk fékk daninn vilja sýnum "
>>>     "framgengt í auknu mæli.")
>>> for tok in g:
>>>     print("{0:10} {1}".format(tok.txt or "", tok.error_description))

Output:

Að         Orðasambandið 'Af gefnu tilefni' var leiðrétt í 'að gefnu tilefni'
gefnu
tilefni
fékk       Endurtekið orð ('fékk') var fellt burt
Daninn     Orð á að byrja á hástaf: 'daninn'
vilja      Orðasambandið 'vilja sýnum framgengt' var leiðrétt í 'vilja sínum framgengt'
sínum
framgengt
í          Orðasambandið 'í auknu mæli' var leiðrétt í 'í auknum mæli'
auknum
mæli
.

To perform full spelling and grammar analysis of a sentence from Python code:

from reynir_correct import check_single
sent = check_single("Páli, vini mínum, langaði að horfa á sjónnvarpið.")
for annotation in sent.annotations:
    print("{0}".format(annotation))

Output:

000-004: P_WRONG_CASE_þgf_þf Á líklega að vera 'Pál, vin minn' / [Pál , vin minn]
009-009: S004   Orðið 'sjónnvarpið' var leiðrétt í 'sjónvarpið'

sent.tidy_text

Output:

'Páli, vini mínum, langaði að horfa á sjónvarpið.'

The annotation.start and annotation.end properties (here start is 0 and end is 4) contain the 0-based indices of the first and last tokens to which the annotation applies. The annotation.start_char and annotation.end_char properties contain the indices of the first and last character to which the annotation applies, within the original input string.

P_WRONG_CASE_þgf_þf and S004 are error codes.

For more detailed, low-level control, the check_errors() function supports options and can produce various types of output:

from reynir_correct import check_errors
x = "Páli, vini mínum, langaði að horfa á sjónnvarpið."
options = { "input": x, "annotations": True, "format": "text" }
s = check_errors(**options)
for i in s.split("\n"):
   print(i)

Output:

Pál, vin minn, langaði að horfa á sjónvarpið.
000-004: P_WRONG_CASE_þgf_þf Á líklega að vera 'Pál, vin minn' | 'Páli, vini mínum,' -> 'Pál, vin minn' | None
009-009: S004   Orðið 'sjónnvarpið' var leiðrétt í 'sjónvarpið' | 'sjónnvarpið' -> 'sjónvarpið' | None

The following options can be specified:

An overview of error codes is available here.

Prerequisites

GreynirCorrect runs on CPython 3.8 or newer, and on PyPy 3.8 or newer. It has been tested on Linux, macOS and Windows. The PyPi package includes binary wheels for common environments, but if the setup on your OS requires compilation from sources, you may need

$ sudo apt-get install python3-dev

...or something to similar effect to enable this.

Installation

To install this package (assuming you have Python >= 3.8 with pip installed):

$ pip install reynir-correct

If you want to be able to edit the source, do like so (assuming you have git installed):

$ git clone https://github.com/mideind/GreynirCorrect
$ cd GreynirCorrect
$ # [ Activate your virtualenv here if you have one ]
$ pip install -e .

The package source code is now in GreynirCorrect/src/reynir_correct.

The command line tool

After installation, the corrector can be invoked directly from the command line:

$ correct input.txt output.txt

...or:

$ echo "Þinngið samþikkti tilöguna" | correct
Þingið samþykkti tillöguna

Input and output files are encoded in UTF-8. If the files are not given explicitly, stdin and stdout are used for input and output, respectively.

Empty lines in the input are treated as sentence boundaries.

By default, the output consists of one sentence per line, where each line ends with a single newline character (ASCII LF, chr(10), "\n"). Within each line, tokens are separated by spaces.

The following (mutually exclusive) options can be specified on the command line:

The CSV and JSON formats of token objects are identical to those documented for the Tokenizer package.

The JSON format of whole-sentence annotations is identical to the one documented for the Yfirlestur.is HTTPS REST API.

Type correct -h to get a short help message.

Command Line Examples

$ echo "Atvinuleysi jógst um 3%" | correct
Atvinnuleysi jókst um 3%

$ echo "Barnið vil grænann lit" | correct --csv
6,"Barnið",""
6,"vil",""
6,"grænan",""
6,"lit",""
0,"",""

Note how vil is not corrected, as it is a valid and common word, and the correct command does not perform grammar checking by default.

$ echo "Pakkin er fyrir hestin" | correct --json
{"k":"BEGIN SENT"}
{"k":"WORD","t":"Pakkinn"}
{"k":"WORD","t":"er"}
{"k":"WORD","t":"fyrir"}
{"k":"WORD","t":"hestinn"}
{"k":"END SENT"}

To perform whole-sentence grammar checking and annotation as well as spell checking, use the --grammar option:

$ echo "Ég kláraði verkefnið þrátt fyrir að ég var þreittur." | correct --grammar
{
   "original":"Ég kláraði verkefnið þrátt fyrir að ég var þreittur.",
   "corrected":"Ég kláraði verkefnið þrátt fyrir að ég var þreyttur.",
   "tokens":[
      {"k":6,"x":"Ég","o":"Ég"},
      {"k":6,"x":"kláraði","o":" kláraði"},
      {"k":6,"x":"verkefnið","o":" verkefnið"},
      {"k":6,"x":"þrátt fyrir","o":" þrátt fyrir"},
      {"k":6,"x":"að","o":" að"},
      {"k":6,"x":"ég","o":" ég"},
      {"k":6,"x":"var","o":" var"},
      {"k":6,"x":"þreyttur","o":" þreittur"},
      {"k":1,"x":".","o":"."}
   ],
   "annotations":[
      {
         "start":6,
         "end":6,
         "start_char":35,
         "end_char":37,
         "code":"P_MOOD_ACK",
         "text":"Hér er réttara að nota viðtengingarhátt
            sagnarinnar 'vera', þ.e. 'væri'.",
         "detail":"Í viðurkenningarsetningum á borð við 'Z'
            í dæminu 'X gerði Y þrátt fyrir að Z' á sögnin að vera
            í viðtengingarhætti fremur en framsöguhætti.",
         "suggest":"væri"
      },
      {
         "start":7,
         "end":7,
         "start_char":38,
         "end_char":41,
         "code":"S004",
         "text":"Orðið 'þreittur' var leiðrétt í 'þreyttur'",
         "detail":"",
         "suggest":"þreyttur"
      }
   ]
}

The output has been formatted for legibility - each input sentence is actually represented by a JSON object in a single line of text, terminated by newline.

Note that the corrected field only includes token-level spelling correction (in this case þreittur -> þreyttur), but no grammar corrections. The grammar corrections are found in the annotations list. To apply corrections and suggestions from the annotations, replace source text or tokens (as identified by the start and end, or start_char and end_char properties) with the suggest field, if present.

Tests

To run the built-in tests, install pytest, cd to your GreynirCorrect subdirectory (and optionally activate your virtualenv), then run:

$ python -m pytest

Acknowledgements

Parts of this software are developed under the auspices of the Icelandic Government's 5-year Language Technology Programme for Icelandic, which is managed by Almannarómur and described here (English version here).

Copyright and License

Copyright © 2023 Miðeind ehf.

GreynirCorrect's original author is Vilhjálmur Þorsteinsson.

This software is licensed under the MIT License:

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

GreynirCorrect indirectly embeds the Database of Icelandic Morphology (Beygingarlýsing íslensks nútímamáls), abbreviated BÍN, along with directly using Ritmyndir, a collection of non-standard word forms. Miðeind does not claim any endorsement by the BÍN authors or copyright holders.

The BÍN source data are publicly available under the CC BY-SA 4.0 license, as further detailed here in English and here in Icelandic.

In accordance with the BÍN license terms, credit is hereby given as follows:

Beygingarlýsing íslensks nútímamáls. Stofnun Árna Magnússonar í íslenskum fræðum. Höfundur og ritstjóri Kristín Bjarnadóttir.