[datatable-help] Avoiding print when using := ?

[Steve Lianoglou]

Howdy folks,

On Fri, Sep 14, 2012 at 8:33 AM, Matthew Dowle <mdowle at mdowle.plus.com> wrote:
>
> Hi Steve,
>
> Your commits are fantastic!

Thanks :-)

> Yes just feel free to go ahead and make
> progress, no need to check with me first.

> On `history` and `interactive()`, yes great idea.

I actually committed a first (likely too simple) hack at this to SVN .. witness:

R> library(data.table)
R> dt <- data.table(a=letters[1:5], score=rnorm(5))
R> dt
   a      score
1: a -0.7509320
2: b  0.9898114
3: c  0.2222932
4: d -0.8143132
5: e -0.9038881

R> dt[, zz := runif(5)]   ## ... crickets ...
R> dt
   a      score        zz
1: a -0.7509320 0.7769256
2: b  0.9898114 0.3341632
3: c  0.2222932 0.1541943
4: d -0.8143132 0.7989931
5: e -0.9038881 0.1405818

One downside is that as your R session gets long in the tooth, calling
history() becomes more onerous since `history` is implemented by
writing all of the history to a temp file, then reading the entire
file, then just picking off the last line ... I think the length of
the history that's saved is stored in `R_HISTSIZE` (see ?history) and
defaults to 512, so .. maybe not so terrible? ... or ... ?

-steve

-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact