Re: Replace specific element with specific value.

*To*: mathgroup at smc.vnet.net*Subject*: [mg99633] Re: Replace specific element with specific value.*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Sun, 10 May 2009 05:13:19 -0400 (EDT)*References*: <gu3av0$1f$1@smc.vnet.net>

A simple replacement can do this: data /. {x -> x + xx, y -> y + yy, z -> z + zz} if x,y or z may also be present in the first term and replacement there is not desired: data /. {{a_, x} -> {a, x + xx}, {a_, y} -> {a, y + yy}, {a_, z} -> {a, z + zz}} Cheers -- Sjoerd On May 9, 9:22 am, nick.... at mssm.edu wrote: > I tried this code, it gives me right and wrong results spreeded into > nested lists. > > data = {{0, 2}, {2, x}, {3, 4}, {4, 6}, {6, y}, {8, 9}, {9, z}} > > Table[{#1, #2 + Which[#2 === j, i, #2 =!= j, 0]} & @@@ > data, {i, {xx, yy, zz}}, {j, {x, y, z}}] > > needed output: > > {0, 2}, {2, x+xx}, {3, 4}, {4, 6}, {6, y+yy}, {8, 9}, {9, z+zz}} > > While searching only the second element of each list, if x is found > add xx and if y is found add yy to it etc. > > How to. Thanks in advance, Nick.