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<p style="margin: 1.2em 0px ! important;">Everyone,</p>
<p style="margin: 1.2em 0px ! important;">The <code
style="font-size: 0.85em; font-family:
Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em;
padding: 0px 0.3em; white-space: nowrap; border: 1px solid
rgb(234, 234, 234); background-color: rgb(248, 248, 248);
border-radius: 3px; display: inline;">varA...varZ</code>
construct is borrowed from STATA syntax. Probably a reason why
it got into subset() in the first place, though definitely not
very R-like. In fact I’ve never come across this construct in R
before and had no idea it was actually working either!</p>
<p style="margin: 1.2em 0px ! important;">I’m not sure <code
style="font-size: 0.85em; font-family:
Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em;
padding: 0px 0.3em; white-space: nowrap; border: 1px solid
rgb(234, 234, 234); background-color: rgb(248, 248, 248);
border-radius: 3px; display: inline;">dt[, .SD,
.SDcols=list(varA...varZ)]</code> is less typing, less prone
to error, or more readable than <code style="font-size: 0.85em;
font-family: Consolas,Inconsolata,Courier,monospace;margin:
0px 0.15em; padding: 0px 0.3em; white-space: nowrap; border:
1px solid rgb(234, 234, 234); background-color: rgb(248, 248,
248); border-radius: 3px; display: inline;">dt[, .SD,
.SDcols=names(dt)[1:24]</code> and using indices is also more
flexible (what about if we want more complex sequences). I can
see one use case for this syntax though if <code
style="font-size: 0.85em; font-family:
Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em;
padding: 0px 0.3em; white-space: nowrap; border: 1px solid
rgb(234, 234, 234); background-color: rgb(248, 248, 248);
border-radius: 3px; display: inline;">dt</code> might change
over time but variables always come in known sequences.</p>
<p style="margin: 1.2em 0px ! important;">Not sure we should
really encourage it — but agreed with Arun, if it’s in
base::subset() then no reason why not.</p>
<p style="margin: 1.2em 0px ! important;">—Mel.</p>
<p style="margin: 1.2em 0px ! important;">On 2/10/2015 1:50 PM,
Arunkumar Srinivasan wrote:</p>
<blockquote style="margin: 1.2em 0px;border-left: 4px solid
rgb(221, 221, 221); padding: 0px 1em; color: rgb(119, 119, 119);
quotes: none;">
<p style="margin: 1.2em 0px ! important;">I had the same
reaction when I found out ‘subset’ already did this :-).</p>
<h2 style="margin: 1.3em 0px 1em; padding: 0px; font-weight:
bold;font-size: 1.4em; border-bottom: 1px solid rgb(204, 204,
204);"
id="i-ve-the-same-impression-that-it-s-a-bit-odd-even-though-some-people-prefer-it-">I’ve
the same impression that it’s a bit odd, even though some
people prefer it.. </h2>
<p style="margin: 1.2em 0px ! important;">Arun</p>
<p style="margin: 1.2em 0px ! important;">On 10 Feb 2015 at
19:39:29, Chris Neff (<a class="moz-txt-link-abbreviated" href="mailto:caneff@gmail.com">caneff@gmail.com</a>) wrote:</p>
<blockquote style="margin: 1.2em 0px;border-left: 4px solid
rgb(221, 221, 221); padding: 0px 1em; color: rgb(119, 119,
119); quotes: none;">
<p style="margin: 1.2em 0px ! important;">Wow, didn’t realize
that worked! So there is precedent then. It just looks funny
to me, but you are right it is easily avoided. I just didn’t
want to see more divergence from subset and data.frame
logic, but since this already works with subset that’s fine.<br>
On Tue Feb 10 2015 at 1:34:03 PM Arunkumar Srinivasan <a
href="http://mailto:aragorn168b@gmail.com">aragorn168b@gmail.com</a>
wrote:</p>
<pre style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;font-size: 1em; line-height: 1.2em; overflow: auto;margin: 1.2em 0px;"><code style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;white-space: pre; border-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em;display: block; padding: 0.5em; color: rgb(51, 51, 51); background: none repeat scroll 0% 0% rgb(248, 248, 255);">Chris,
But what’s the problem? You can simply not use it?
It’s not that uncommon. `base::subset()` does this.
--
Arun
On 10 Feb 2015 at 19:31:43, Chris Neff (<a class="moz-txt-link-abbreviated" href="mailto:caneff@gmail.com">caneff@gmail.com</a>) wrote:
</code></pre>
<blockquote style="margin: 1.2em 0px;border-left: 4px solid
rgb(221, 221, 221); padding: 0px 1em; color: rgb(119, 119,
119); quotes: none;">
<pre style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;font-size: 1em; line-height: 1.2em; overflow: auto;margin: 1.2em 0px;"><code style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;white-space: pre; border-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em;display: block; padding: 0.5em; color: rgb(51, 51, 51); background: none repeat scroll 0% 0% rgb(248, 248, 255);">I don't like this idea. It adds extra that it doesn't need to. Doing it with column numbers is more straightforward, and if all you have is names you can get numbers by doing match() or whatever and then getting the sequence with seq(). Having a sequence of column names is odd.
On Tue Feb 10 2015 at 1:28:25 PM Arunkumar Srinivasan <a class="moz-txt-link-rfc2396E" href="mailto:aragorn168b@gmail.com"><aragorn168b@gmail.com></a> wrote:
Farrel,
It could be useful. Please file an issue on the github project page. Thanks.
--
Arun
On 10 Feb 2015 at 01:08:46, Farrel Buchinsky (<a class="moz-txt-link-abbreviated" href="mailto:fjbuch@gmail.com">fjbuch@gmail.com</a>) wrote:
</code></pre>
<blockquote style="margin: 1.2em 0px;border-left: 4px solid
rgb(221, 221, 221); padding: 0px 1em; color: rgb(119, 119,
119); quotes: none;">
<pre style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;font-size: 1em; line-height: 1.2em; overflow: auto;margin: 1.2em 0px;"><code style="font-size: 0.85em; font-family: Consolas,Inconsolata,Courier,monospace;margin: 0px 0.15em; padding: 0px 0.3em; white-space: nowrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-radius: 3px; display: inline;white-space: pre; border-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em;display: block; padding: 0.5em; color: rgb(51, 51, 51); background: none repeat scroll 0% 0% rgb(248, 248, 255);"> 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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-- <br>
Melanie BACOU<br>
International Food Policy Research Institute<br>
Snr. Program Manager, HarvestChoice<br>
Work +1(202)862-5699<br>
E-mail <a class="moz-txt-link-abbreviated" href="mailto:m.bacou@cgiar.org">m.bacou@cgiar.org</a><br>
Visit <a class="moz-txt-link-abbreviated" href="http://www.harvestchoice.org">www.harvestchoice.org</a> <br>
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