Re: Map onto one column of a matrix

*To*: mathgroup at smc.vnet.net*Subject*: [mg95532] Re: [mg95485] Map onto one column of a matrix*From*: "Scot T. Martin" <smartin at deas.harvard.edu>*Date*: Wed, 21 Jan 2009 06:43:47 -0500 (EST)*References*: <200901201044.FAA16641@smc.vnet.net>

Daniel, this may be what you're after: {#1, f[#2]} & @@@ data On Tue, 20 Jan 2009, D. Grady wrote: > Hi, suppose we've got a matrix > > data = {{a, b}, {c, d}}; > > and we want to map a function onto just the second column, so we want > to end up with > > {{a, f[b]}, {c, f[d]}}. > > The best way I've found to do this is with MapAt: > > MapAt[f, data, Table[{i, 2}, {i, Length@data}]] > > Is there a better way? I keep hoping there's some notation similar to > what's used in Part that lets you refer to a whole column with All, > like data[[All,2]]. Thanks! > > -Daniel > >