Re: pattern matching all list elements but last
- To: mathgroup at smc.vnet.net
- Subject: [mg54569] Re: [mg54539] pattern matching all list elements but last
- From: "David Park" <djmp at earthlink.net>
- Date: Wed, 23 Feb 2005 03:11:39 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Trevor,
ls = {{1}, {2, 3}, {4, 5, 6}, {7, 8, 9, 10}};
Join[100 + Drop[#, -1], {Last[#]}] & /@ ls
{{1}, {102, 3}, {104, 105, 6}, {107, 108, 109, 10}}
David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/
From: Trevor Baca [mailto:trevorbaca at gmail.com]
To: mathgroup at smc.vnet.net
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.