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MathGroup Archive 2005

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Re: pattern matching all list elements but last

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54598] Re: [mg54539] pattern matching all list elements but last
  • From: yehuda ben-shimol <bsyehuda at gmail.com>
  • Date: Thu, 24 Feb 2005 03:21:03 -0500 (EST)
  • References: <200502220924.EAA10849@smc.vnet.net>
  • Reply-to: yehuda ben-shimol <bsyehuda at gmail.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,
Although your question was focused on the pattern matching style I
would like to not ethat you can also use the functional programming
style
e.g.
 ls = {{1}, {2,3}, {4,5,6}, {7,8,9,10}};
Flatten[{100 + Most[#], Last[#]}] & /@ ls
and get the same result
yehuda



On Tue, 22 Feb 2005 04:24:35 -0500 (EST), Trevor Baca
<trevorbaca at gmail.com> wrote:
> 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.
> 
>


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