From: Paul Brannan <pbrannan@...>
Date: 2007-09-24T22:50:00+09:00
Subject: Re: I am new to Ruby and I could use some expert advice as to how I can make this code run faster.

Since you didn't provide python code for us to compare against, I can only
assume that the code to which you refer is from this thread:

http://groups.google.com/group/comp.lang.python/browse_thread/thread/fa33727aa3a6751f/7efd9f93b7834a23?lnk=st&q=python+scramble&rnum=4#7efd9f93b7834a23

I don't know which version of the code you used, but here's a version
using String#tr which is equivalent to Michael Spencer's version using
translate:

def scramble_tr(fname)
    f = File.new(fname, "rb")
    _fname = fname + ".scrambled"
    begin
        File.exist?(_fname) if File.delete(_fname)
    rescue
    end
    ff = File.new(_fname, "wb+")
    for l in f
        l.tr!("\x0-\x7f", "\x80-\xff")
        ff.write(l)
    end
    f.close()
    ff.close()
end 

Since I'm on a much slower machine, I used a 1MB file:

cout@bean:~/tmp$ ruby test5.rb testfile
                          user     system      total        real
scramble             10.780000   0.120000  10.900000 ( 11.514982)
_scramble            11.630000   0.050000  11.680000 ( 11.918237)
scramble_tr           0.250000   0.030000   0.280000 (  0.416945)

If you're going to do a comparison, please make sure you aren't
comparing apples to oranges.  The language shootout isn't perfect, but
it does a pretty good job:

http://shootout.alioth.debian.org/

Hope this helps,

Paul