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.