help levenshtein
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Title

    levenshtein -- Calculate the Levenshtein edit distance between two
    strings.

Syntax

    Calculate the Levenshtein edit distance between two strings

        levenshtein string1 string2

    Calculate the Levenshtein edit distances between two string vectors

        levenshtein varname1 varname2 [if] [in], generate(newvarname)


Description

    levenshtein calculate the Levenshtein edit distance(s) between two
    strings or two vectors of strings. The Levenshtein edit distance is
    defined as the minimum number of insertions, deletions, or substitutions
    necessary to change one string into the other. For example, the
    Levenshtein edit distance between "mitten" and "fitting" is 3, since the
    following three edits change one into the other, and it is impossible to
    do it with fewer than three edits:

        1. mitten -> fitten (substitution of 'f' for 'm')

        2. fitten -> fittin (substitution of 'i' for 'e')

        3. fittin -> fitting (insert 'g' at the end)


Examples

    1. Calculate the Levenshtein edit distance between "mitten" and
    "fitting":

       . levenshtein mitten fitting


    2. Calculate the Levenshtein edit distance between two string vectors:

       . sysuse auto, clear

       . decode foreign, gen(foreign_string)

       . levenshtein make foreign_string, gen(edit_dist)


Notes

    levenshtein is implemented as a plugin in order to minimize memory
    requirements and to maximize speed.  Unfortunately, plugins are specific
    to the hardware architecture and software framework of your computer,
    i.e., plugins are not cross-platform.  Define a platform by two
    characteristics: machine type and operating system.  Stata stores these
    characteristics in c(machine_type) and c(os), respectively. levenshtein
    supports the following platforms at this time:

         Machine type                   Operating system
         PC                             Windows
         PC (64-bit x86-64)             Unix
         Macintosh                      MacOSX
         Macintosh (Intel 64-bit)       MacOSX


Saved results

    r(distance) The Levenshtein edit distance


Acknowledgements

    The algorithm used to calculate the Levenshtein edit distance is based on
    a Python extension written by David Necas (Yeti).  His code is publicly
    available at
    http://code.google.com/p/pylevenshtein/source/browse/trunk/Levenshtein.c.

    Thanks to James Beard for helpful suggestions and feedback.


Author

    Julian Reif, University of Chicago

    jreif@uchicago.edu


Also see

    strgroup