[datatable-help] create empty data.table

[Frank Erickson]

You can make a wrapper for something like

> DT <- data.table(date=Sys.Date()[0],id=character(0),value=numeric(0))

# examine structure
> str(DT)
Classes ‘data.table’ and 'data.frame':  0 obs. of  3 variables:
 $ date :Class 'Date'  num(0)
 $ id   : chr
 $ value: num
 - attr(*, ".internal.selfref")=<externalptr>

# try appending
> str(rbind(DT,list(Sys.Date(),"A",1)))
Classes ‘data.table’ and 'data.frame':  1 obs. of  3 variables:
 $ date : Date, format: "2015-07-23"
 $ id   : chr "A"
 $ value: num 1
 - attr(*, ".internal.selfref")=<externalptr>

--Frank

On Thu, Jul 23, 2015 at 5:51 AM, statquant3 <statquant at outlook.com> wrote:

> I wanted to create a function that creates an empty data.table with
> specified
> column types.
> emptyDT <- function(colNames,colTypes){...}
> I would call
> emptyDT(c('date','id','value'),c('Date','Character','Numeric'))
>
> Is there something available for this already ?
>
>
>
>
> --
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