spellchecker

Spellchecker

Yet another spellchecker written in go.

• Spellchecker
  • Features:
  • Installation
  • Usage
  • Benchmarks
    • Test set 1:
    • Test set 2:

Features:

• very compact database: ~1 MB for 30,000 unique words
• average time to fix a single word: ~35 µs
• achieves about 70–74% accuracy on Peter Norvig’s test sets (see benchmarks)

Installation

go get -v github.com/f1monkey/spellchecker

Usage

Quick start

func main() {
	// Create a new instance
	sc, err := spellchecker.New(
		"abcdefghijklmnopqrstuvwxyz1234567890", // allowed symbols, other symbols will be ignored
		spellchecker.WithMaxErrors(2) 			// see options.go
	)
	if err != nil {
		panic(err)
	}

	// Load data from any io.Reader
	in, err := os.Open("data/sample.txt")
	if err != nil {
		panic(err)
	}
	sc.AddFrom(in)

	// Add words manually
	sc.Add("lock", "stock", "and", "two", "smoking", "barrels")

	// Check if a word is valid
	result := sc.IsCorrect("coffee")
	fmt.Println(result) // true

	// Correct a single word
	fixed, err := sc.Fix("awepon")
	if err != nil && !errors.Is(err, spellchecker.ErrUnknownWord) {
		panic(err)
	}
	fmt.Println(fixed) // weapon

	// Find up to 10 suggestions for a word
	matches, err := sc.Suggest("rang", 10)
	if err != nil && !errors.Is(err, spellchecker.ErrUnknownWord) {
		panic(err)
	}
	fmt.Println(matches) // [range, orange]

Options

See options.go for the list of available options.

Save/load

	sc, err := spellchecker.New("abc")

	// Save data to any io.Writer
	out, err := os.Create("data/out.bin")
	if err != nil {
		panic(err)
	}
	sc.Save(out)

	// Load data back from io.Reader
	in, err = os.Open("data/out.bin")
	if err != nil {
		panic(err)
	}
	sc, err = spellchecker.Load(in)
	if err != nil {
		panic(err)
	}

Custom score function

You can provide a custom scoring function if needed:

	var fn spellchecker.FilterFunc = func(src, candidate []rune, cnt int) (float64, bool) {
		// you can calculate Levenshtein distance here (see defaultFilterFunc in options.go for example)

		return 1.0, true // constant score
	}

	sc, err := spellchecker.New("abc", spellchecker.WithFilterFunc(fn))
	if err != nil {
		// handle err
	}

	// After loading a spellchecker from a file,
	// you need to set the function again:
	sc, err = spellchecker.Load(inFile)
	if err != nil {
		// handle err
	}

	err = sc.WithOpts(spellchecker.WithFilterFunc(fn))
	if err != nil {
		// handle err
	}

Benchmarks

Tests are based on data from Peter Norvig's article about spelling correction

Test set 1:

Running tool: /usr/bin/go test -benchmem -run=^$ -bench ^Benchmark_Norvig1$ github.com/f1monkey/spellchecker -count=1

goos: linux
goarch: amd64
pkg: github.com/f1monkey/spellchecker
cpu: 13th Gen Intel(R) Core(TM) i9-13980HX
Benchmark_Norvig1-32    	     348	   3385868 ns/op	        74.44 success_percent	       201.0 success_words	       270.0 total_words	  830803 B/op	   15504 allocs/op
PASS
ok  	github.com/f1monkey/spellchecker	3.723s

Test set 2:

Running tool: /usr/bin/go test -benchmem -run=^$ -bench ^Benchmark_Norvig2$ github.com/f1monkey/spellchecker -count=1

goos: linux
goarch: amd64
pkg: github.com/f1monkey/spellchecker
cpu: 13th Gen Intel(R) Core(TM) i9-13980HX
Benchmark_Norvig2-32    	     231	   4935406 ns/op	        71.25 success_percent	       285.0 success_words	       400.0 total_words	 1270755 B/op	   21801 allocs/op
PASS
ok  	github.com/f1monkey/spellchecker	4.057s