> We actually had a more advanced mechanism for computing
> string distances in an old version of odepkg that was based
> on Levenshtein metric
>

That's on the strings package too, named edit_distance

http://hg.code.sf.net/p/octave/strings/file/db1ee7036df0/inst/editdistance.m

Hi,

We actually had a more advanced mechanism for computing
string distances in an old version of odepkg that was based
on Levenshtein metric

The code can be recovered from the repository here:

c++ version

or here

m-file

the function fuzzy_compare finds the best match of a given string within a set of allowed strings and would be useful in this context.

See the end of scripts/pkg/private/get_forge_pkg.m.  I'm pretty sure I wrote it and it is pretty dumb.

    ## Try a simplistic method to determine similar names.
    function d = fdist (x)
      len1 = length (name);
      len2 = length (x);
      if (len1 <= len2)
        d = sum (abs (name(1:len1) - x(1:len1))) + sum (x(len1+1:end));
      else
        d = sum (abs (name(1:len2) - x(1:len2))) + sum (name(len2+1:end));
      endif
    endfunction
    dist = cellfun ("fdist", t);
    [~, i] = min (dist);
    error ("get_forge_pkg: package not found: ""%s"".  Maybe you meant ""%s?""",
           name, t{i});

Additional characters add a cost penalty assuming a reference of 0.  This can easily overwhelm distances in the first half of the calculation.

When a user tries to install a Forge package, but gets the name wrong, a single name suggestion is shown:

>> pkg install -forge springs
error: get_forge_pkg: package not found: "springs".  Maybe you meant "strings?"

This works very well when the string length matches exactly. But when a single character is added or omitted, the metric it is using for similarity falls apart as it seems to be assigning a higher cost to having a different string length than to having every single character being wrong:

>> pkg install -forge imagel
error: get_forge_pkg: package not found: "imagel".  Maybe you meant "signal?"

>> pkg install -forge signa
error: get_forge_pkg: package not found: "signa".  Maybe you meant "video?"

>> pkg install -forge signals
error: get_forge_pkg: package not found: "signals".  Maybe you meant "sockets?"

>> pkg install -forge communication
error: get_forge_pkg: package not found: "communication".  Maybe you meant "generate_html?"

Also not sure why this case returns "zeromq" instead of "signal":

>> pkg install -forge sizzzz
error: get_forge_pkg: package not found: "sizzzz".  Maybe you meant "zeromq?"