Closes #1243: fixes bug whereby using .GRP variable created a variabl…

…e with leading period (.)

Bug fix added to README

fixing test to reflect update

Adding .BY to clean-up

R/data.table.R

@@ -893,7 +893,7 @@ chmatch2 <- function(x, table, nomatch=NA_integer_) {
             if (is.name(jsub)) {
                 # j is a single unquoted column name
                 if (jsub!=".SD") {
-                    jvnames = gsub("^[.]([NI])$","\\1",as.character(jsub))
+                    jvnames = gsub("^[.](N|I|GRP|BY)$","\\1",as.character(jsub))
                     # jsub is list()ed after it's eval'd inside dogroups.
                 }
             } else if (is.call(jsub) && as.character(jsub[[1L]]) %chin% c("list",".")) {
@@ -904,7 +904,7 @@ chmatch2 <- function(x, table, nomatch=NA_integer_) {
                     if (is.null(jvnames)) jvnames = rep.int("", length(jsubl)-1L)
                     for (jj in seq.int(2L,length(jsubl))) {
                         if (jvnames[jj-1L] == "" && mode(jsubl[[jj]])=="name")
-                            jvnames[jj-1L] = gsub("^[.]([NI])$","\\1",deparse(jsubl[[jj]]))
+                            jvnames[jj-1L] = gsub("^[.](N|I|GRP|BY)$","\\1",deparse(jsubl[[jj]]))
                         # TO DO: if call to a[1] for example, then call it 'a' too
                     }
                     setattr(jsubl, "names", NULL)  # drops the names from the list so it's faster to eval the j for each group. We'll put them back aftwards on the result.

README.md

@@ -240,6 +240,8 @@
 
   63. Row numbers are not printed in scientific format. Closes [#1167](https://github.com/Rdatatable/data.table/issues/1167). Thanks to @jangorecki for the PR.
 
+  64. Using `.GRP` unnamed in `j` now returns a variable named `GRP` instead of `.GRP` as the period was causing issues. Same for `.BY`. Closes [#1243](https://github.com/Rdatatable/data.table/issues/1243); thanks to @MichaelChirico for the PR.
+
 #### NOTES
 
   1. Clearer explanation of what `duplicated()` does (borrowed from base). Thanks to @matthieugomez for pointing out. Closes [#872](https://github.com/Rdatatable/data.table/issues/872).

inst/tests/tests.Rraw

@@ -2172,7 +2172,7 @@ setkey(DT,a)
 test(783, DT[,.I,by=a]$I, 1:8)
 test(784, DT[,.I[which.max(b)],by=a], data.table(a=1:4,V1=INT(2,4,6,8),key="a"))
 test(785, DT[J(2:4),.I,by=a%%2L], data.table(a=rep(0:1,c(4,2)),I=INT(3,4,7,8,5,6)))
-test(786, DT[J(c(3,2,4)),list(.I,.GRP),by=.EACHI], data.table(a=rep(c(3L,2L,4L),each=2),I=INT(5,6,3,4,7,8),.GRP=rep(1:3,each=2L)))
+test(786, DT[J(c(3,2,4)),list(.I,.GRP),by=.EACHI], data.table(a=rep(c(3L,2L,4L),each=2),I=INT(5,6,3,4,7,8),GRP=rep(1:3,each=2L)))
 test(787, DT[J(3:2),`:=`(i=.I,grp=.GRP),by=.EACHI][,list(i,grp)], data.table(i=INT(NA,NA,3:6,NA,NA),grp=INT(NA,NA,2,2,1,1,NA,NA)))
 
 # New not-join (a.k.a. not-select, since not just for data.table i but integer, logical and character too)