Differing output for function moved from ruby 1.8 to 1.9

Ruby
1

Sup, fools?

This is the Levenshtein function I’m gankin’ for my file comparison
project (see “40 million comparison…” thread):

Levenshtein calculator

Author: Paul B. ([email protected])

Modified slightly by John Perkins:

– removed $KCODE call

def distance(str1, str2)

unpack_rule = ‘C*’
s = str1.unpack(unpack_rule)
t = str2.unpack(unpack_rule)
n = s.length
m = t.length

return m if (0 == n) # stop the madness if either string is empty
return n if (0 == m)

d = (0…m).to_a
x = nil

(0…n).each do |i|
e = i + 1
(0…m).each do |j|
cost = (s[i] == t[j]) ? 0 : 1
x = [
d[j + 1] + 1, # insertion
e + 1, # deletion
d[j] + cost # substitution
].min
d[j] = e
e = x
end
d[m] = x
end

return x
end

When I ran this with test data in ruby 1.8 the output was 969, but
when I ran it on a 1.9 install the output was 1011. I’m aware that
some of the rules have changed, especially with arrays. Does anyone
see where the discrepancy lies, because I sure as heck don’t. The
files didn’t change so the distance shouldn’t either. Thanks for all
your help in advance.

2

Here’s an idea: a migration script that detects when and where a
script will break after the big 1.9/2 move.

I’m not that good of a rubyist, but I know there’s about a dozen
people reading these that could have it done by Friday night (I’m
looking at YOU, _why).

3

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

DJ Jazzy L. wrote:
| Here’s an idea: a migration script that detects when and where a
| script will break after the big 1.9/2 move.
|
| I’m not that good of a rubyist, but I know there’s about a dozen
| people reading these that could have it done by Friday night (I’m
| looking at YOU, _why).

Maybe the chance to get your 15 minutes of fame, and deepen your
understanding of Ruby at the same time.

Phillip G.
Twitter: twitter.com/cynicalryan
Blog: http://justarubyist.blogspot.com

Use recursive procedures for recursively-defined data structures.
~ - The Elements of Programming Style (Kernighan & Plaugher)
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4

I think a no-brainer prerequisite to this script would be 2.0 actually
being released.