About
It's a implementation of Jaro-Winkler distance algorithm, it uses C extension and will fallback to pure Ruby version in JRuby. Both implementation supports UTF-8 string.
Installation
gem install jaro_winkler
Usage
require 'jaro_winkler'
JaroWinkler.distance "MARTHA", "MARHTA"
# => 0.9611
JaroWinkler.distance "MARTHA", "marhta", ignore_case: true
# => 0.9611
JaroWinkler.distance "MARTHA", "MARHTA", weight: 0.2
# => 0.9778
# Force the strategy
JaroWinkler.c_distance "MARTHA", "MARHTA" # C extension
JaroWinkler.r_distance "MARTHA", "MARHTA" # Pure Ruby
Both implementations support UTF-8 string.
Options
| Name | Type | Default | Note |
|---|---|---|---|
| ignore_case | boolean | false | All lower case characters are converted to upper case prior to the comparison. |
| weight | number | 0.1 | A constant scaling factor for how much the score is adjusted upwards for having common prefixes. |
| threshold | number | 0.7 | The prefix bonus is only added when the compared strings have a Jaro distance above the threshold. |
Why This?
There is also another gem named fuzzy-string-match, it uses the same algorithm and both provides C and Ruby implementation.
I reinvent this wheel because of the naming in fuzzy-string-match such as getDistance breaks convention, and some weird code like a1 = s1.split( // ) (s1.chars could be better), furthermore, it's bugged (see table below).
Compare with other gems
| jaro_winkler | fuzzystringmatch | hotwater | amatch | |
|---|---|---|---|---|
| UTF-8 Suport | Yes | Pure Ruby only | ||
| Native | Yes | Yes | Yes | Yes |
| Pure Ruby | Yes | Yes | ||
| Speed | Medium | Fast | Medium | Low |
| Bug Found | Yes | Yes |
For Bug Found, I made a rake task to build the table below, the source code is in Rakefile:
| str_1 | str_2 | origin | jaro_winkler | fuzzystringmatch | hotwater | amatch |
|---|---|---|---|---|---|---|
| "henka" | "henkan" | 0.9667 | 0.9667 | 0.9722 | 0.9667 | 0.9444 |
| "al" | "al" | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| "martha" | "marhta" | 0.9611 | 0.9611 | 0.9611 | 0.9611 | 0.9444 |
| "jones" | "johnson" | 0.8324 | 0.8324 | 0.8324 | 0.8324 | 0.7905 |
| "abcvwxyz" | "cabvwxyz" | 0.9583 | 0.9583 | 0.9583 | 0.9583 | 0.9583 |
| "dwayne" | "duane" | 0.84 | 0.84 | 0.84 | 0.84 | 0.8222 |
| "dixon" | "dicksonx" | 0.8133 | 0.8133 | 0.8133 | 0.8133 | 0.7667 |
| "fvie" | "ten" | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
- The origin result is from the original C implementation by the author of the algorithm.
- Test data are borrowed from fuzzy-string-match's rspec file.
Benchmark
Pure Ruby
| user | system | total | real | |
|---|---|---|---|---|
| jaro_winkler | 12.750000 | 0.030000 | 12.780000 | ( 12.782842) |
| fuzzystringmatch | 16.240000 | 0.030000 | 16.270000 | ( 16.287380) |
- jaro_winkler (1.2.3)
- fuzzy-string-match (0.9.6)
Native
| user | system | total | real | |
|---|---|---|---|---|
| jaro_winkler | 0.390000 | 0.000000 | 0.390000 | ( 0.392408) |
| fuzzystringmatch | 0.150000 | 0.000000 | 0.150000 | ( 0.151552) |
| hotwater | 0.320000 | 0.000000 | 0.320000 | ( 0.317740) |
| amatch | 0.960000 | 0.010000 | 0.970000 | ( 0.964803) |
- jaro_winkler (1.2.3)
- fuzzy-string-match (0.9.6)
- hotwater (0.1.2)
- amatch (0.3.0)
Todo
- Make it faster
- Adjusting word table (Reference to original C implementation.)