---
name: "Text::Levenshtein::Damerau"
section: "3pm"
platform: "linux"
package: "libtext-levenshtein-damerau-perl"
version: "0.41-3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Text::Levenshtein::Damerau"
---

# Text::Levenshtein::Damerau(3pm)

Damerau Levenshtein edit distance.

## NAME

Text::Levenshtein::Damerau - Damerau Levenshtein edit distance.

## SYNOPSIS

```
        use Text::Levenshtein::Damerau;
        use warnings;
        use strict;
        my @targets = ('fuor','xr','fourrrr','fo');
        # Initialize Text::Levenshtein::Damerau object with text to compare against
        my $tld = Text::Levenshtein::Damerau->new('four');
        print $tld->dld($targets[0]);
        # prints 1
        my $tld = $tld->dld({ list => \@targets });
        print $tld->{'fuor'};
        # prints 1
        print $tld->dld_best_match({ list => \@targets });
        # prints fuor
        print $tld->dld_best_distance({ list => \@targets });
        # prints 1
        # or even more simply
        use Text::Levenshtein::Damerau qw/edistance/;
        use warnings;
        use strict;

        print edistance('Neil','Niel');
        # prints 1
```

## DESCRIPTION

Returns the true Damerau Levenshtein edit distance of strings with adjacent transpositions. Useful for fuzzy matching, DNA variation metrics, and fraud detection.

Defaults to using Pure Perl Text::Levenshtein::Damerau::PP, but has an XS addon Text::Levenshtein::Damerau::XS for massive speed imrovements. Works correctly with utf8 if backend supports it; known to work with `"Text::Levenshtein::Damerau::PP"` and `"Text::Levenshtein::Damerau::XS"`.

```
        use utf8;
        my $tld = Text::Levenshtein::Damerau->new('ⓕⓞⓤⓡ');
        print $tld->dld('ⓕⓤⓞⓡ');
        # prints 1
```

## CONSTRUCTOR

### new

Creates and returns a `"Text::Levenshtein::Damerau"` object. Takes a scalar with the text (source) you want to compare against.

```
        my $tld = Text::Levenshtein::Damerau->new('Neil');
        # Creates a new Text::Levenshtein::Damerau object $tld
```

## METHODS

### $tld-\>dld

**Scalar** Argument: Takes a string to compare with.

Returns: an integer representing the edit distance between the source and the passed argument.

**Hashref** Argument: Takes a hashref containing:

- •

  list =\> \\@array (array ref of strings to compare with)

- •

  *OPTIONAL* max\_distance =\> `$int` (only return results with `$int` distance or less).

- •

  *OPTIONAL* backend =\> 'Some::Module::its\_function' Any module that will take 2 arguments and returns an int. If the module fails to load, the function doesn't exist, or the function doesn't return a number when passed 2 strings, then `"backend"` remains unchanged.

  ```
          # Override defaults and use Text::Levenshtein::Damerau::PP's pp_edistance()
          $tld->dld({ list=> \@list, backend => 'Text::Levenshtein::Damerau::PP::pp_edistance');
          # Override defaults and use Text::Levenshtein::Damerau::XS's xs_edistance()
          use Text::Levenshtein::Damerau;
          requires Text::Levenshtein::Damerau::XS;
          ...
          $tld->dld({ list=> \@list, backend => 'Text::Levenshtein::Damerau::XS::xs_edistance');
  ```

Returns: hashref with each word from the passed list as keys, and their edit distance (if less than max\_distance, which is unlimited by default).

```
        my $tld = Text::Levenshtein::Damerau->new('Neil');
        print $tld->dld( 'Niel' );
        # prints 1
        #or if you want to check the distance of various items in a list
        my @names_list = ('Niel','Jack');
        my $tld = Text::Levenshtein::Damerau->new('Neil');
        my $d_ref = $tld->dld({ list=> \@names_list }); # pass a list, returns a hash ref
        print $d_ref->{'Niel'}; #prints 1
        print $d_ref->{'Jack'}; #prints 4
```

### $tld-\>dld\_best\_match

Argument: an array reference of strings.

Returns: the string with the smallest edit distance between the source and the array of strings passed.

Takes distance of `$tld` source against every item in `@targets`, then returns the string of the best match.

```
        my $tld = Text::Levenshtein::Damerau->new('Neil');
        my @name_spellings = ('Niel','Neell','KNiel');
        print $tld->dld_best_match({ list=> \@name_spellings });
        # prints Niel
```

### $tld-\>dld\_best\_distance

Arguments: an array reference of strings.

Returns: the smallest edit distance between the source and the array reference of strings passed.

Takes distance of `$tld` source against every item in the passed array, then returns the smallest edit distance.

```
        my $tld = Text::Levenshtein::Damerau->new('Neil');
        my @name_spellings = ('Niel','Neell','KNiel');
        print $tld->dld_best_distance({ list => \@name_spellings });
        # prints 1
```

## EXPORTABLE METHODS

### edistance

Arguments: source string and target string.

- •

  *OPTIONAL 3rd argument* int (max distance; only return results with `$int` distance or less). 0 = unlimited. Default = 0.

Returns: int that represents the edit distance between the two argument. -1 if max distance is set and reached.

Wrapper function to take the edit distance between a source and target string. It will attempt to use, in order:

- •

  Text::Levenshtein::Damerau::XS **xs\_edistance**

- •

  Text::Levenshtein::Damerau::PP **pp\_edistance**

```
        use Text::Levenshtein::Damerau qw/edistance/;
        print edistance('Neil','Niel');
        # prints 1
```

## SEE ALSO

- •

  \<https://github.com/ugexe/Text--Levenshtein--Damerau\> *Repository*

- •

  \<http://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein\_distance\> *Damerau levenshtein explanation*

- •

  Text::Fuzzy *Regular levenshtein distance*

## BUGS

Please report bugs to:

\<https://rt.cpan.org/Public/Dist/Display.html?Name=Text-Levenshtein-Damerau\>

## AUTHOR

Nick Logan \<*ug@skunkds.com*\>

## LICENSE AND COPYRIGHT

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.