Re: Map onto a column

*To*: mathgroup at smc.vnet.net*Subject*: [mg125492] Re: Map onto a column*From*: Murta <rodrigomurtax at gmail.com>*Date*: Thu, 15 Mar 2012 00:34:27 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201203130802.DAA12753@smc.vnet.net> <jjpbje$pbu$1@smc.vnet.net>

I agree that some solution like that b = MapAt[f,a,{All,2}] would be much more elegant. Maybe in Mathematica 9?? On Mar 14, 2:50 am, Sseziwa Mukasa <muk... at gmail.com> wrote: > Transpose the matrix and MapAt the appropriate row then Transpose back: > > Transpose[MapAt[f,Transpose[a],2]] > > On Mar 13, 2012, at 4:02 AM, Sly Pandemia wrote: > > > > > > > > > Is there a neat way to map a function onto a specific column in an > > array? > > > For example if I have > > > a = {{1,2,3},{4,5,6},{7,8,9}} > > > and I want to map f onto the second element in each row. I would > > normally use > > > b = Map[MapAt[f,#,2]&,a] > > > but this seems a bit awkward. I would expect to be able to use > > > b = MapAt[f,a,{All,2}] > > > but this appears to be illegal syntax. > > > Is there any way to do what I want with a single Map/MapAt function?

**References**:**Map onto a column***From:*Sly Pandemia <slypandemia@gmail.com>