[datatable-help] rbind() vs. rbindlist() behavior/warning

[Arunkumar Srinivasan]

I am not aware of the status now after eddi's recent edits. "rbindlist" initially only checked the type of the first data.table's columns. But now I guess with eddi's changes, it does look-down and decide based on class hierarchy. That is, if column 1 of dt1 is integer, but of dt2 is numeric, it's now "numeric", but before it was "integer". I guess this'll affect the speed. I've not done any benchmarking yet. But I'm guessing it'll be slower than at least the previous version. 

Eddi, any thoughts on this? 

Arun


On Saturday, November 9, 2013 at 6:38 PM, G See wrote:

> Isn't rbindlist(myList) faster than do.call(rbind, myList)?
> 
> Garrett
> 
> On Sat, Nov 9, 2013 at 11:33 AM, Arunkumar Srinivasan
> <aragorn168b at gmail.com (mailto:aragorn168b at gmail.com)> wrote:
> > GSee, I find this a bit confusing at the moment as well - the convergence of
> > "rbind" and "rbindlist" and therefore the future of "rbindlist".
> > 
> > `rbindlist` gained speed (to some extent) by assuming things like this and
> > skipping checks in the first place. So, should we include checks like this?
> > Also, if "rbind" and/or "rbindlist" are made to do the exact same thing,
> > then, what's the purpose of "rbindlist"?
> > 
> > Any thoughts?
> > 
> > Arun
> > 
> > On Saturday, November 9, 2013 at 6:29 PM, Eduard Antonyan wrote:
> > 
> > Fyi, it's not well documented, but setting use.names=FALSE in rbind would
> > replicate rbindlist behavior.
> > 
> > I think it's a reasonable FR - if/when all of rbind code goes into C, it
> > would be trivial to add.
> > 
> > On Nov 9, 2013 10:51 AM, "G See" <gsee000 at gmail.com (mailto:gsee000 at gmail.com)> wrote:
> > 
> > Hi,
> > 
> > Please note the inconsistency between the behavior of rbind() and
> > rbindlist() below.
> > 
> > m1 <- as.data.table(mtcars)
> > m2 <- copy(m1)
> > rbind(m1[, .SD[1], by=cyl], m2) # Gives warning and binds by name
> > rbindlist(list(m1[, .SD[1], by=cyl], m2)) # no warning, and does NOT
> > bind by name
> > 
> > What do you think about making them have the same behavior and/or
> > warning? Personally, I prefer the behavior of rbind(), and would
> > prefer to see a warning if column names are ignored like they are with
> > rbindlist().
> > 
> > Thanks,
> > Garrett
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> > 
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> 
> 
> 


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