[datatable-help] Unexpected behavior in setnames()

[Arunkumar Srinivasan]

Sure, here's an example of what I was trying to explain: 

Suppose: 
DT <- data.table(x=1:5, y=1:5, x=6:10)

Then, 

DT[, c(1,3), with=FALSE] # gives correct subset
DT[, c("x", "x"), with=FALSE] # gives column 1 twice - wrong

DT[, .SD, .SDcols=c("x", "x")] # gives column 1 twice - wrong result
DT[, .SD, .SDcols=c(1,3)] # gives column 1 twice - wrong result - but *should provide right result if "ambiguity" is the only concern.


Arun


On Friday, November 8, 2013 at 9:29 PM, Steve Lianoglou wrote:

> > Steve,
> > Maybe, but it's just getting started :) - we now have to decide what's
> > ambiguous!
> > 
> 
> 
> So close, yet so far ...
> 
> > Ex: Is subsetting by column number considered ambiguous (By definition of
> > ambiguous, probably not)? But then it'd be inconsistent with subsetting when
> > column names are provided.. So, should we prioritise consistency over
> > function in this scenario?
> > 
> 
> 
> Sorry, can you provide examples of each?
> 
> I'd imagine doing anything by column number is unambiguous, but I'm
> not sure how you can subset by column index and by column name in a
> "similar" fashion.
> 
> I mean dt[[1]] should work no matter what, dt[['a']] would work only
> if there is only one column named 'a' ... but I don't think this is
> what you are talking about?
> 
> Sorry if I'm being obtuse,
> 
> -steve
> 
> -- 
> Steve Lianoglou
> Computational Biologist
> Bioinformatics and Computational Biology
> Genentech
> 
> 


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