Re: pattern matching all list elements but last
- To: mathgroup at smc.vnet.net
- Subject: [mg54559] Re: [mg54539] pattern matching all list elements but last
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Wed, 23 Feb 2005 03:11:31 -0500 (EST)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
ls={{1},{2,3},{4,5,6},{7,8,9,10}};
ls /. {a___,b_Integer} :> {Sequence@@({a}+100),b}
{{1},{102,3},{104,105,6},{107,108,109,10}}
Bob Hanlon
>
> From: "Trevor Baca" <trevorbaca at gmail.com>
To: mathgroup at smc.vnet.net
> Date: 2005/02/22 Tue AM 04:24:35 EST
> To: mathgroup at smc.vnet.net
> Subject: [mg54559] [mg54539] pattern matching all list elements but last
>
> 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.
>
>