Nice! I don't see why not. It's a nice use of .EACHI. Perhaps you'd like to file it as a FR? It'd be easy to keep track then, for later, when Matt'll also have a look..
Arun From: Gabor Grothendieck [email protected] Reply: Gabor Grothendieck [email protected] Date: June 30, 2014 at 8:41:51 PM To: Arunkumar Srinivasan [email protected] Cc: Stavros Macrakis (Σταῦρος Μακράκης) [email protected], datatable-help [email protected] Subject: Re: [datatable-help] Speeding up column references with roll One other comment. I wonder if .EACHI could mean by each row if there were no join specified so this: library(data.table) DT <- data.table( v1 = factor(c("a", "a", "a", "b", "b", "b")), v2 = c(1, 1, 6, 3, 4, 5), v3 = c("a", "b", "c", "a", "b", "c"), stringsAsFactors=FALSE ) DT[, c(.SD, split(v2, v1)), by = 1:nrow(DT)][, -1, with = FALSE] could be written: DT[, c(.SD, split(v2, v1)), by = .EACHI] or maybe even: DT[, split(v2, v1), by = c(names(DT), .EACHI)] On Mon, Jun 30, 2014 at 2:21 PM, Gabor Grothendieck <[email protected]> wrote: > On Mon, Jun 30, 2014 at 1:00 PM, Arunkumar Srinivasan > <[email protected]> wrote: >> Once again, has been fixed in 1.9.3. Now join requires `by=.EACHI` >> (explicit) to perform a by-without-by. >> https://github.com/Rdatatable/data.table/blob/master/README.md > > The README would be easier to understand if DT was not undefined in > the README. As it stands none of the examples are runnable. -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com
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