From: Peter Thoman <peter.thoman@...>
Date: 2006-02-07T18:28:30+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?
>
I'm definitely *not* feeling sharp (10 AM here and I haven't slept yet) 
but here's my try:

arr = [3,:x,1,:y,2]       # => [3, :x, 1, :y, 2]
sorted = arr.select { |v| v.class == Fixnum }.sort     # => [1, 2, 3]
arr.map { |v| v.class == Fixnum ? sorted.shift : v }   # => [1, :x, 2, 
:y, 3]

Of course, substitute conditions as appropriate.

- Peter