[datatable-help] there is no package called ‘xts’

[Eduard Antonyan]

@Michael, in the last expression, you probably forgot a J:

frame[J(unique(id)), mult = "last"]


On Tue, Apr 23, 2013 at 7:41 PM, Michael Nelson <
michael.nelson at sydney.edu.au> wrote:

> From the help for data.table::last
>
>  If x is a data.table, the last row as a one row data.table. Otherwise,
> whatever xts::last returns.
>
>
> calling lapply(.SD, last) will call last on each column in .SD. Columns
> within a data.table aren't  data.tables thus `xts::last` is called.  xts is
> on the suggests list for data.table,
>
> you could use
>
> install.packages('data.table, dependencies = 'Suggests')
>
> or manually installed xts.
>
> OR
>
> frame[, last(.SD), by = id]
>
> would work without needing xts
>
> as would
>
> frame[, .SD[.N], by = id]
>
> or without having to construct .SD (which is time consuming)
>
> frame[frame[, .I[.N],by = id]$V1]
>
> or
>
> setkey(frame, id)
>
> frame[unique(id), mult = 'last']
>
> ________________________________________
> From: datatable-help-bounces at lists.r-forge.r-project.org [
> datatable-help-bounces at lists.r-forge.r-project.org] on behalf of Sam
> Steingold [sds at gnu.org]
> Sent: Wednesday, 24 April 2013 7:57 AM
> To: datatable-help at lists.r-forge.r-project.org
> Subject: [datatable-help] there is no package called ‘xts’
>
> Hi,
> I got this:
>
> > dt <- frame[, lapply(.SD, last) ,by=id]
> Finding groups (bysameorder=TRUE) ... done in 0.126secs. bysameorder=TRUE
> and o__ is length 0
> Optimized j from 'lapply(.SD, last)' to 'list(last(country),
> last(language), last(browser), last(platform), last(uatype),
> last(behavior))'
> Starting dogroups ... Error in loadNamespace(name) : there is no package
> called ‘xts’
> Calls: [ -> [.data.table -> last -> :: -> getExportedValue -> asNamespace
> -> getNamespace -> tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
> >
>
> the help for last does mention xts, but I don't have it installed.
> do I need to?
>
> --
> Sam Steingold (http://sds.podval.org/) on Ubuntu 12.10 (quantal) X
> 11.0.11300000
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