[datatable-help] finding dt columns by partial name

[Bacou, Melanie]

Hi Carl,
I'm not 100% sure what you're after, but I'm assuming you're looking for 
something like:

dt[, .SD, .SDcols=names(dt) %like% "Call1"]

That's syntax you can use to select all columns of a data.table 
containing "Call1".
--Mel.

On 3/10/2016 2:00 PM, carlsutton wrote:
> Hi
>
> I did search but did not see an answer.
>
> I have a dt with 580 + columns.  many of the columns will have variations of
> a name to specifically identify them, ie, call23,Call111, doCall.now, etc.
> Since I cannot recall the exact column names I have been resorting to    df
> <- data.frame(dt)  and then
>                               a <- grep("Call1", colnames(df))
>                              colnames(df[a])
>
> which then returns the columns names containing Call1.
>
> If I try this with the data table ie, colnames(dt[a]) I get null.
>
> Any suggestions?  I am feeling rather ignorant converting a dt back to a
> data frame and available memory may be a concern further down the road.
>
> Carl Sutton
>
>
>
> -----
> Carl Sutton
> --
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