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On 14/02/14 15:07, Yike Lu wrote:<br>
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cite="mid:CAO=aP+dZmtC5d1c62dTeSfDRSn0Fb_XWstpRA6kA5uTd=eaS5w@mail.gmail.com"
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<div dir="ltr">Thanks for the info guys! Wondering if there's any
way I can help?<br>
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<br>
Thanks for your offer. The function iradix in forder.c needs
copying and tweaking to become i64radix (8 passes instead of 4), or
making general so that 4 or 8 can be passed in. Should also check
first how the bit64 package sorts integer64. Then in bmerge.c add a
case to the switch for integer64 to cast to long long, add tests to
tests.Rraw for grouping and joining, update documentation (.Rd)
files and add checks to init.c.<br>
<br>
Is that something you could do? If you are rusty on C I don't mind
guiding you through.<br>
<br>
Matt<br>
<br>
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cite="mid:CAO=aP+dZmtC5d1c62dTeSfDRSn0Fb_XWstpRA6kA5uTd=eaS5w@mail.gmail.com"
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<div class="gmail_quote">On Wed, Feb 12, 2014 at 11:17 AM, <a
moz-do-not-send="true" href="mailto:caneff@gmail.com">caneff@gmail.com</a>
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:caneff@gmail.com" target="_blank">caneff@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Yes this
isn't a data.table criticism, just a bit64 one in general.
<div class="HOEnZb">
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On Wed Feb 12 2014 at 11:39:47 AM, Matt Dowle <<a
moz-do-not-send="true"
href="mailto:mdowle@mdowle.plus.com" target="_blank">mdowle@mdowle.plus.com</a>>
wrote:</div>
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.8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div><br>
Sometimes we take the hard road in data.table, to
get to a better place. Once bit64::integer64 is
fully supported, it'll be much easier. All the
recent radix work for double applies almost
automatically to integer64 for example, but that
radix work had to be done first.</div>
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<br>
On 12/02/14 16:26, <a moz-do-not-send="true"
href="mailto:caneff@gmail.com" target="_blank">caneff@gmail.com</a>
wrote:<br>
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<blockquote type="cite">FYI (and this is a long
outstanding argument) this is why I don't like the
bit64 package. These sorts of errors happen
silently. I understand that data.table can't use
the other integer64 package, but at least there it
is obvious when things are being coerced. <br>
<div><br>
</div>
<div>In my situations, if I am grouping by a
int64, it is usually either an ID so I can just
make it a character vector instead, or it is
something where I don't mind lost precision so I
just make it numeric. </div>
<br>
<div>On Wed Feb 12 2014 at 11:22:40 AM, Matt Dowle
<<a moz-do-not-send="true"
href="mailto:mdowle@mdowle.plus.com"
target="_blank">mdowle@mdowle.plus.com</a>>
wrote:</div>
<blockquote style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex"> <br>
Hi,<br>
<br>
You're doing nothing wrong. Although you can
load integer64 using fread<br>
and create them directly, data.table's grouping
and keys don't work on<br>
them yet. Sorry, just not yet implemented.
Because integer64 are<br>
internally stored as type double (a good idea
by package bit64),<br>
data.table sees them internally as double and
doesn't catch that the<br>
type isn't supported yet (hence no error message
such as you get for<br>
type 'complex'). The particular integer64
numbers in this example are<br>
quite small so will use the lower bits. In
double, those are the most<br>
precise part of the significand, which would
explain why only one group<br>
comes out here since data.table groups and joins
floating point data<br>
within tolerance.<br>
<br>
Matt<br>
<br>
On 06/02/14 23:38, Yike Lu wrote:<br>
> After a long hiatus, I am back to using
data.table. Unfortunately,<br>
> I've encountered a problem. Am I doing
something wrong here?<br>
><br>
> require(data.table)<br>
><br>
> dt = data.table(idx = 1:100 %% 3, 1:100)<br>
> dt[, list(sum(V2)), by = idx]<br>
> # normal<br>
><br>
> require(bit64)<br>
><br>
> dt2 = data.table(idx = integer64(100) +
1:100 %% 3, 1:100)<br>
> dt2[, list(sum(V2)), by = idx]<br>
> # only has one group:<br>
> # idx V1<br>
> #1: 1 5050<br>
><br>
<br>
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