<div dir="ltr">with = FALSE will let you use literal column names</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Apr 24, 2013 at 3:29 PM, Sam Steingold <span dir="ltr"><<a href="mailto:sds@gnu.org" target="_blank">sds@gnu.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">What do I do if I want to operate on several columns?<br>
E.g.,<br>
--8<---------------cut here---------------start------------->8---<br>
length(names(dt)) = 25<br>
myvars = c("col1","col4","col7")<br>
myid = "user"<br>
setkeyv(dt,myid)<br>
--8<---------------cut here---------------end--------------->8---<br>
and I want to summarize columns in myvars by myid.<br>
the point is that nowhere in the code the literal "col4" or "user" may<br>
appear.<br>
<br>
Thanks.<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Sam Steingold (<a href="http://sds.podval.org/" target="_blank">http://sds.podval.org/</a>) on Ubuntu 12.10 (quantal) X 11.0.11300000<br>
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