Re: Apply a function to parts of a list

*To*: mathgroup at smc.vnet.net*Subject*: [mg110312] Re: Apply a function to parts of a list*From*: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>*Date*: Sun, 13 Jun 2010 04:09:19 -0400 (EDT)*References*: <huvk7i$rtn$1@smc.vnet.net>

Is this simple enough: In[41]:= list = {{"A", 1}, {"B", 2}, {"C", 3}, {"D", 4}, {"E", 5}, {"F", 6}, {"G", 7}, {"H", 8}, {"I", 9}, {"J", 10}}; In[42]:= list /. {i_, j_} -> {i, j/2} Out[42]= {{"A", 1/2}, {"B", 1}, {"C", 3/2}, {"D", 2}, {"E", 5/ 2}, {"F", 3}, {"G", 7/2}, {"H", 4}, {"I", 9/2}, {"J", 5}} ??? Cheers -- Sjoerd On Jun 12, 11:32 am, Rui <rui.r... at gmail.com> wrote: > I have always done very ugly code when trying to do something > seemingly simple and basic such as applying a function to subparts of a list. > Simple example, I want to divide by 2 all the second elements of a > list > {{a, 5}, {b, 6}, ...} --> {{a, 5/2}, ...} > > My ideas: > Transpose -> MapAt/Map -> Transpose > Build the sublist with Part and then rebuild it > Use Map and a function like #[[All, 2]] and then rebuild it. > > I don't like any solution. I wanted to know if there's anything simple > that I'm overseing > > Thanks guys