[datatable-help] can one name a collection of columns by specifying just the first and the last column

[Jeff Zemla]

I don't think you can reference them by name, but if they are in a list you
can reference them by index, e.g.

dt[,colnames(dt)[3:5],with=FALSE]

will get you height, weight and shoe.size

or alternatively

dt[,.SD,.SDcols=colnames(dt)[3:5]]

does the same thing



On Mon, Feb 9, 2015 at 7:08 PM, Farrel Buchinsky <fjbuch at gmail.com> wrote:

> So lets say one has a data.table with the following columns
>
> first.name, last.name, height, weight, shoe.size, eye.color, hair.length,
> appendage.size, ear.length
>
> If one wanted to just include weight through hair.length one would have to
> go something such as this
>
> dt[,list(weight, shoe.size, eye.color, hair.length)]
>
> Is there a way to do something along the lines of
>
> dt[,list(weight...hair.length)]
>
> If so, can you direct me to the documentation? If not can you build it? Is
> it difficult? Some data.tables have many columns.
>
> Thanking you in anticipation.
>
> Farrel
>
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