Re: pattern matching all list elements but last
- To: mathgroup at smc.vnet.net
- Subject: [mg54560] Re: [mg54539] pattern matching all list elements but last
- From: "Ingolf Dahl" <ingolf.dahl at telia.com>
- Date: Wed, 23 Feb 2005 03:11:31 -0500 (EST)
- Reply-to: <ingolf.dahl at telia.com>
- Sender: owner-wri-mathgroup at wolfram.com
Hi Trevor,
This does the trick
ls /. {{a___Integer, b_Integer} :> {Sequence @@ ({a} + 100), b}}
Best regards
Ingolf Dahl
ingolf.dahl at telia.com
Sweden
-----Original Message-----
From: Trevor Baca [mailto:trevorbaca at gmail.com]
To: mathgroup at smc.vnet.net
Subject: [mg54560] [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.