@mnel, I'm not sure I understand your output. Yours is different from the correct output, but it is also different from Kevin's. Basically, dt[, max(y), by=by] has no effect on yours and just returns back dt?
Arun On Thursday, December 19, 2013 at 3:50 AM, Michael Nelson wrote: > Using > data.table 1.8.11 (Fresh install from r-forge today) > R version 3.0.2 (2013-09-25) > Platform: x86_64-w64-mingw32/x64 (64-bit) > > I get > > by max > 1: 0.7 0.01464054 > 2: 0.4 0.87328871 > 3: 0.4 -1.02794620 > > On both runs. > > > > > ________________________________________ > From: [email protected] > (mailto:[email protected]) > [[email protected] > (mailto:[email protected])] on behalf of > Kevin Ushey [[email protected] (mailto:[email protected])] > Sent: Thursday, 19 December 2013 12:54 PM > To: [email protected] > (mailto:[email protected]) > Subject: [datatable-help] 'by' on a numeric column produces inconsistent > output > > I'm cross-posting this from the GitHub mirror: > https://github.com/arunsrinivasan/datatable/issues/2 > > For reference, I only see this with the latest RForge version of > data.table (1.8.11), not the CRAN version of data.table. > > ----- > > library(data.table, lib="/Users/kevinushey/Library/R/3.1/library") > set.seed(32) > n <- 3 > dt <- data.table( > y=rnorm(n), > by=round( rnorm(n), 1) > ) > > dt[, > list(max=max(y, na.rm=TRUE)), > by=list(by) > ] > > dt[, > list(max=max(y, na.rm=TRUE)), > by=list(by) > ] > > produces the output > > > dt[, > + list(max=max(y, na.rm=TRUE)), > + by=list(by) > + ] > by max > 1: 0.4 0.01464054 > 2: 0.4 0.87328871 > 3: 0.7 -1.02794620 > > > > dt[, > + list(max=max(y, na.rm=TRUE)), > + by=list(by) > + ] > by max > 1: 0.4 0.8732887 > 2: 0.7 -1.0279462 > > For some reason, the first return is wrong, while the second (and all > subsequent) output is correct. Any idea what's going on? > > > sessionInfo() > R Under development (unstable) (2013-12-12 r64453) > Platform: x86_64-apple-darwin13.0.0 (64-bit) > > locale: > [1] en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8 > > attached base packages: > [1] stats graphics grDevices utils datasets methods base > > other attached packages: > [1] data.table_1.8.11 knitr_1.5 devtools_1.4.1.99 > BiocInstaller_1.13.3 > > loaded via a namespace (and not attached): > [1] compiler_3.1.0 digest_0.6.4 evaluate_0.5.1 formatR_0.10 > httr_0.2 memoise_0.1 > [7] parallel_3.1.0 plyr_1.8 RCurl_1.95-4.1 reshape2_1.2.2 > stringr_0.6.2 tools_3.1.0 > [13] whisker_0.3-2 > > --- > > Kevin > _______________________________________________ > datatable-help mailing list > [email protected] > (mailto:[email protected]) > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > _______________________________________________ > datatable-help mailing list > [email protected] > (mailto:[email protected]) > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > >
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