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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.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.