## stringdist

- Approximate matching and string distance calculations for R.
- All distance and matching operations are system- and encoding-independent.
- Built for speed, using openMP for parallel computing.

The package offers the following main functions:

`stringdist`

computes pairwise distances between two input character vectors (shorter one is recycled)
`stringdistmatrix`

computes the distance matrix for one or two vectors
`stringsim`

computes a string similarity between 0 and 1, based on `stringdist`

`amatch`

is a fuzzy matching equivalent of R’s native `match`

function
`ain`

is a fuzzy matching equivalent of R’s native `%in%`

operator
`seq_dist`

, `seq_distmatrix`

, `seq_amatch`

and `seq_ain`

for distances between, and matching of integer sequences.

These functions are built upon `C`

-code that re-implements some common (weighted) string distance functions. Distance functions include:

- Hamming distance;
- Levenshtein distance (weighted)
- Restricted Damerau-Levenshtein distance (weighted, a.k.a. Optimal String Alignment)
- Full Damerau-Levenshtein distance
- Longest Common Substring distance
- Q-gram distance
- cosine distance for q-gram count vectors (= 1-cosine similarity)
- Jaccard distance for q-gram count vectors (= 1-Jaccard similarity)
- Jaro, and Jaro-Winkler distance
- Soundex-based string distance

Also, there are some utility functions:

`qgrams()`

tabulates the qgrams in one or more `character`

vectors.
`seq_qrams()`

tabulates the qgrams (somtimes called ngrams) in one or more `integer`

vectors.
`phonetic()`

computes phonetic codes of strings (currently only soundex)
`printable_ascii()`

is a utility function that detects non-printable ascii or non-ascii characters.

#### C API

Some of `stringdist`

’s underlying `C`

functions can be called directly from `C`

code in other packages. The description of the API can be found by either typing `?stringdist_api`

in the R console or open the vignette directly as follows:

`vignette("stringdist_C-Cpp_api", package="stringdist")`

Examples of packages that link to `stringdist`

can be found here and here.

#### Resources

- A paper on stringdist has been published in the R-journal
- Slides of a talk given at te
*useR!2014* conference.