From: William James <w_a_x_man@...>
Date: 2006-02-07T18:18:21+09:00
Subject: Re: Feeling sharp? Sort an array subset in place.

Michael Judge wrote:
> Here's the situation: I have an array and I'd like to sort certain
> elements in place -- without touching the others.
>
> Unsorted array contents:
>   3 <-- sort me!
>   x
>   1 <-- sort me!
>   y
>   2 <-- sort me!
>
> Sorted array contents
>   1
>   x
>   2
>   y
>   3
>
> See how 1, 2, and 3 played musical chairs?  That's exactly what we
> want. It seems like there should be an easy one, two or three-line way
> to do this given an array and a test condition (for identifying
> elements which need sorting.)
>
> How would you do it?
>
> (My solution was a dirty cheat, it involved building a hash of {from =>
> to} moves, cloning the original array contents, then changing each
> element one at a time. Blah.  There's got to be a sexier way.)

a = [ 3, :x, 1, :y, 2 ]
f=nil
tmp = a.partition{ f=!f }
p tmp.first.sort.zip( tmp.last ).flatten.compact