[datatable-help] duplicated, with a key

[Joseph Voelkel]

Thanks. That makes sense. And apologies for not just checking duplicated.data.table.

-----Original Message-----
From: Matthew Dowle [mailto:mdowlenoreply at virginmedia.com] On Behalf Of Matthew Dowle
Sent: Saturday, March 03, 2012 8:04 PM
To: Joseph Voelkel
Cc: datatable-help at lists.r-forge.r-project.org
Subject: Re: [datatable-help] duplicated, with a key

Yes, that's documented in ?duplicated.data.table.

Matthew

On Sat, 2012-03-03 at 17:53 -0500, Joseph Voelkel wrote:
> Is the second result by design? I found it confusing:
> 
> x<-data.table(a=c(1:5,1:5),b=1:10)
> sum(duplicated(x)) # 0, as expected
> setkey(x,a)
> sum(duplicated(x)) # 5

> Thanks,

> Joe
> 
> Joseph G. Voelkel, Ph.D.
> 
> Graduate Program Chair, Center for Quality and Applied Statistics
> 
> Kate Gleason College of Engineering
> 
> Rochester Institute of Technology
> 
> V 585-475-2231
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> F 585-475-5959
> 
> joseph.voelkel at rit.edu
> 
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