Re: Map onto a column
- To: mathgroup at smc.vnet.net
- Subject: [mg125463] Re: Map onto a column
- From: Sseziwa Mukasa <mukasa at gmail.com>
- Date: Wed, 14 Mar 2012 00:44:57 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <201203130802.DAA12753@smc.vnet.net>
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>
- Map onto a column