[datatable-help] variable column names

[Sam Steingold]

What do I do if I want to operate on several columns?
E.g.,
--8<---------------cut here---------------start------------->8---
length(names(dt)) = 25
myvars = c("col1","col4","col7")
myid = "user"
setkeyv(dt,myid)
--8<---------------cut here---------------end--------------->8---
and I want to summarize columns in myvars by myid.
the point is that nowhere in the code the literal "col4" or "user" may
appear.

Thanks.

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Sam Steingold (http://sds.podval.org/) on Ubuntu 12.10 (quantal) X 11.0.11300000
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