<div dir="ltr">Thanks for pointing that out. I didn't know about (= think to search for) that global option. I think I'll leave it as NA since, as you say, it's reasonably useful.<div><br></div><div>I forgot that people may want to switch to allow.cartesian = TRUE (although I never find myself wanting to use this) after seeing the error. So, a modified (very minor) FR: have the error message suggest switching to nomatch=0 (because this is what I personally find myself switching to after I see the error, though I don't know how common that choice is...).<div>
<br></div><div>I still don't understand the mention of "duplicate key values in i" in the message, as the problem seems to be with duplicated values in x (at least in my example above).</div><div><br></div>
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--Frank</div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Oct 14, 2013 at 12:42 AM, Michael Nelson <span dir="ltr"><<a href="mailto:michael.nelson@sydney.edu.au" target="_blank">michael.nelson@sydney.edu.au</a>></span> wrote:<br>
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The default argument to nomatch is `'getOption("datatable.nomatch")`. The default value for this is `NA`.
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<div>If you want to change this option, simply set `options(datatable.nomatch = 0)`, then the default will be as you want.</div>
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<div>I think the current datatable.nomatch = NA is reasonable, as you are often interested in non-matches as well as matches.</div>
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<div>x[y, nomatch=NA] to give a error in your case, then follow the advice of the error message and run</div>
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<div>x[y, nomatch=NA, allow.cartesian = TRUE]</div>
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<div style="direction:ltr"><font face="Tahoma" color="#000000"><b>From:</b> <a href="mailto:datatable-help-bounces@lists.r-forge.r-project.org" target="_blank">datatable-help-bounces@lists.r-forge.r-project.org</a> [<a href="mailto:datatable-help-bounces@lists.r-forge.r-project.org" target="_blank">datatable-help-bounces@lists.r-forge.r-project.org</a>] on behalf of Frank Erickson [<a href="mailto:FErickson@psu.edu" target="_blank">FErickson@psu.edu</a>]<br>
<b>Sent:</b> Monday, 14 October 2013 1:03 PM<br>
<b>To:</b> data.table source forge<br>
<b>Subject:</b> [datatable-help] possible FR: in x[y], switch to nomatch=0 instead of failing with "Error in vecseq..."<br>
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<div dir="ltr">I don't know if this error shows up in other cases, but I always see it when I'm about to do
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<div><font face="courier new, monospace">x[y,b:=b]</font></div>
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<div>but first want to check how </div>
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<div><font face="courier new, monospace">x[y]</font></div>
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<div>looks before creating or overwriting x$b. Here's an example:</div>
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<div><font face="courier new, monospace">x <- data.table(a=rep(2:3,2),key='a')</font></div>
<div><font face="courier new, monospace">y <- data.table(a=1:4,b=4:1,key='a')</font></div>
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<div><font face="courier new, monospace">x[y] # error</font></div>
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<div><font face="courier new, monospace">x[y,nomatch=0] # ok<br>
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<div><font face="courier new, monospace">x[y,b:=b] # ok</font></div>
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<div>I'd prefer to see the first attempt mapped to the second (with a suitable message), instead of erroring out. What do you all think? Is that reasonable/worthwhile?</div>
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<div>Best,</div>
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<div>Frank</div>
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<div>P.S. One other point, regarding the message itself (reproduced down below): I don't understand why repeated values in i are mentioned.</div>
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<div>-- For x[y] in my example, the problem seems to be coming from x having repeated rows, not i (y in this case); </div>
<div>-- whereas y[x] works just fine (despite the repeated/duplicated values in i...which is x here).</div>
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<div><font face="courier new, monospace">Error in vecseq(f__, len__, if (allow.cartesian) NULL else as.integer(max(nrow(x), : </font></div>
<div><font face="courier new, monospace"> Join results in 6 rows; more than 4 = max(nrow(x),nrow(i)). Check for duplicate key values in i, each of which join to the same group in x over and over again. If that's ok, try including `j` and dropping `by` (by-without-by)
so that j runs for each group to avoid the large allocation. If you are sure you wish to proceed, rerun with allow.cartesian=TRUE. Otherwise, please search for this error message in the FAQ, Wiki, Stack Overflow and datatable-help for advice.</font></div>
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