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pattern matching all list elements but last

• To: mathgroup at smc.vnet.net
• Subject: [mg54539] pattern matching all list elements but last
• From: "Trevor Baca" <trevorbaca at gmail.com>
• Date: Tue, 22 Feb 2005 04:24:35 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

hi mathgroup folks,

let's say ls looks like this:

  ls = {{1}, {2,3}, {4,5,6}, {7,8,9,10}}

is there an elegant way to match all integers *except the last
(rightmost)* in each list and, say, add 100 to each?

  ls /. <magic replacement rule goes here>

or

  ls //. <magic replacement rule goes here>

to give {{1}, {102,3}, {104,105,6}, {107,108,109,10}}?

this works:

  Release[ ls //. {a___, b_Integer, c___, z_Integer} :> {a, Hold[b +
100], c, z} ]

but is there a more elegant pattern, possibly one that avoids the
Hold-Release trick?


trevor.

• Follow-Ups:
  • Re: pattern matching all list elements but last
    • From: yehuda ben-shimol <bsyehuda@gmail.com>
  • Re: pattern matching all list elements but last
    • From: Andrzej Kozlowski <akozlowski@gmail.com>
  • Re: pattern matching all list elements but last
    • From: János <janos.lobb@yale.edu>
  • Re: pattern matching all list elements but last
    • From: DrBob <drbob@bigfoot.com>