[datatable-help] rbind behavior

[Steve Lianoglou]

I think I'm a +1 on doing the xref (like data.frame does), but
emitting a warning when it is done .. unlike data.frame.rbind, which
just does it silently ...

-steve


On Sun, Oct 23, 2011 at 8:08 PM, Matthew Dowle <mdowle at mdowle.plus.com> wrote:
> Ah. Then I think that was deliberate at the time. I sometimes mislabel
> column names and want R to warn me rather than doing silent cross-ref.
> Other times I just think in terms of column order and am not too
> concerned with the names. I don't mind changing it to do cross ref for
> consistency but would like to keep the warning. Views?
>
> On Sun, 2011-10-23 at 14:35 -0400, Steve Lianoglou wrote:
>> I think he means that running data.frame.rbind on these:
>>
>> R> d1 <- data.frame(a=1:10, b=11:20)
>> R> d2 <- data.frame(b=101:120, a=21:30)
>> R> rbind(d1, d2)
>>
>> Will "cross ref" the "a" and "b" columns and stack them correctly on
>> top of each other.
>>
>> Doing the same with two data.table will bind the two together, but
>> won't do the cross-ref. It just gives you a warning that the names
>> didn't match, but rbind's the first to the first, and the second to
>> the second (columns) anyway.
>>
>> -steve
>>
>> On Sun, Oct 23, 2011 at 2:19 PM, Matthew Dowle <mdowle at mdowle.plus.com> wrote:
>> > Hi. Not sure what you mean, example needed please. Is that with v1.7.1 now
>> > on CRAN? There has been some to and fro on chind/rbind in last few
>> > versions.
>> >
>> >> Hi Matthew,
>> >>
>> >> Not sure if this is planned or inadvertent, but rbind matches up named
>> >> columns with data.frames but doesn't with data.table (data.table does give
>> >> the friendly warning).
>> >>
>> >> Thanks as always for your excellent package,
>> >>
>> >> Damian
>> >>
>> >>
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>> >
>> >
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>>
>>
>>
>
>
>



-- 
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