From: Michael Gaunnac <mlgaunnac@...>
Date: 2004-10-08T22:57:20+09:00
Subject: A sort_by descending sort

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Perhaps this has already been covered, but I discovered this idiom for =
doing a descending sort using sort_by.

arr =3D Array.new
(0..20).each {|i| arr.push sprintf('%02d', i)}
p arr
#=3D>["00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "10", =
"11", "12", "13", "14", "15", "16", "17", "18", "19", "20"]

arr =3D arr.sort_by {|i| [i.slice(0,2).tr('0-9','9876543210')]}  # =
descending sort using 9's complement

p arr
#=3D>["20", "19", "18", "17", "16", "15", "14", "13", "12", "11", "10", =
"09", "08", "07", "06", "05", "04", "03", "02", "01", "00"]

Mike
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