Hello Matthew, <br><br><div class="gmail_quote">2011/10/2 Matthew Dowle <span dir="ltr"><<a href="mailto:mdowle@mdowle.plus.com">mdowle@mdowle.plus.com</a>></span><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">
On Thu, 2011-09-29 at 13:33 -0500, Branson Owen wrote:<br>
> "Many data sets do not easily fit into a single data frame, such as<br>
> inherently multiple-table data (e.g. fourth-corner problem and other<br>
> trait-based data sets). Storing such data in a single data frame<br>
> results in either large numbers of meaningless missing values or<br>
> storage of redundant information. The multitable package introduces<br>
> new data storage objects called data.lists, which are extensions of<br>
> data.frames. As data.lists can be coerced to data.frames, they can be<br>
> used with all R functions that accept an object that is coercible to a<br>
> data.frame (e.g. lm; plot; lme; and many more). The multitable package<br>
> also provides several mechanisms for simplifying the manipulation of<br>
> data.list objects."<br>
> [data.list] <a href="http://cran.r-project.org/web/packages/multitable/index.html" target="_blank">http://cran.r-project.org/web/packages/multitable/index.html</a><br>
<br>
</div>I read through the vignette, looks very interesting.<br>
<div class="im"><br>
> [Feature Request<br>
> #202] <a href="https://r-forge.r-project.org/tracker/index.php?func=detail&aid=202&group_id=240&atid=978" target="_blank">https://r-forge.r-project.org/tracker/index.php?func=detail&aid=202&group_id=240&atid=978</a><br>
> [Discussion]<br>
> <a href="http://r.789695.n4.nabble.com/Suggest-a-cool-feature-Use-data-table-like-a-sorted-indexed-data-list-td2544213.html" target="_blank">http://r.789695.n4.nabble.com/Suggest-a-cool-feature-Use-data-table-like-a-sorted-indexed-data-list-td2544213.html</a><br>
<br>
</div>I thought that thread was largely solved. v1.5.2 came after that (I<br>
think) which made grouping work on list() columns. #202 was then changed<br>
to be just 'matrix as columns'. You can already have any sized matrix<br>
(or data.table, or anything) as an element in a data.table (as an<br>
element of a list() column). Not sure if that helps at all. multitable<br>
seems to be about combining together a database of tables into one<br>
object (i.e. different)?<br>
<br></blockquote><div><br></div><div>Oh, sorry, I was testing the syntax like: </div><div><br></div><div>DT = data.table(A = 1:2, B = list('a', 2i))</div><div><br></div><div>It didn't work, and I though this feature has not been implemented. Thank you for pointing it out with a good example. </div>
<div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
> DT = data.table(a=1:3)<br>
> DT$obj = list(matrix(1:3,3),data.table(letters[1:4],1:4),data.table(letters[1:2],1:6))<br>
> setkey(DT,a)<br>
> DT[J(3),obj,mult="first"] # keyed data.list?<br>
[[1]]<br>
V1 V2<br>
[1,] a 1<br>
[2,] b 2<br>
[3,] a 3<br>
[4,] b 4<br>
[5,] a 5<br>
[6,] b 6<br>
<div class="im"><br></div><div class="im">
> I don't know whether the multitable's author is aware of data.table.<br>
> I will write to make suggestions to the multitable author:<br>
> at least, I think it should be an easy change for him to make<br>
> data.list an extension of data.table instead of data.frame, and will<br>
> make multitable package directly inherit data.table's power. Any<br>
> thoughts before I approach Steve? or it would be better to let<br>
> data.table team raise this idea to him? :)<br>
<br>
</div>That would be great if you could approach. Thanks. Would be great to<br>
leverage the synergies.<br></blockquote><div><br></div><div>Sure thing, no problem. I will approach Steve tomorrow with interesting ideas, and let you what he thought if he replies. </div></div><br><div>Best regards,</div>