Re: pattern matching all list elements but last

• To: mathgroup at smc.vnet.net
• Subject: [mg54567] Re: [mg54539] pattern matching all list elements but last
• From: DrBob <drbob at bigfoot.com>
• Date: Wed, 23 Feb 2005 03:11:37 -0500 (EST)
• References: <200502220924.EAA10849@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```ls={{1},{2,3},{4,5,6},{7,8,9,10}};
Replace[ls,{a___,b_}:>{Sequence@@(100+{a}),b},{1}]

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

Bobby

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.
>
>
>
>

--
DrBob at bigfoot.com
www.eclecticdreams.net

```

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