From: William James <w_a_x_man@...>
Date: 2007-05-03T02:35:08+09:00
Subject: Re: Help with rather simple method

On May 2, 11:26 am, Deniz Dogan <kristn...@nospam.com> wrote:
> Hello.
>
> I'm trying to come up with the "best", most Ruby-ish way to write a
> method such as this one:
>
> # This method replaces randomly selected characters in 'string' with new
> # randomly selected characters of [A-Za-z0-9]. However, it does not
> # replace any character with the character itself, i.e., it does not
> # replace any "a" with "a". Also, no position in the string will ever be
> # replaced twice.
> # 'string' is the String to perform the replacing on.
> # 'amount' is the amount of different characters to replace.
> def random_replace(string, amount)
>    ...
> end
>
> You don't have to care about any error checking of course.
>
> Any ideas? The solution I've come up with (but which is yet to be
> implemented) does not feel Ruby-ish at all and could probably be
> implemented in pretty much any other programming language.
>
> And no, this is not school work, no matter what you think.
>
> -Deniz Dogan


def random_replace(string, amount)
  locations = (0...string.size).to_a
  amount.times{
    p = locations.slice!( rand( locations.size ) )
    chars = ('a'..'z').to_a + ('A'..'Z').to_a +
      ('0'..'9').to_a - [ string[p,1] ]
    string[p] = chars[ rand( chars.size ) ]
  }
end

s = 'foo bar'
random_replace( s, 3 )
puts s