Fix for #481 (and #734, duplicate). Fix for ":=" that was missed earl…

…ier.

README.md

@@ -226,7 +226,7 @@ We moved from R-Forge to GitHub on 9 June 2014, including history.
 
   32.  Fixed an edge case in `DT[order(.)]` internal optimisation to be consistent with base. Closes [#696](https://github.com/Rdatatable/data.table/issues/696). Thanks to Michael Smith and Garrett See for reporting.
 
-  33.  `DT[, list(list(.)), by=.]` returns correct results in R >=3.1.0 as well. The bug was due to recent (welcoming) changes in R v3.1.0 where `list(.)` does not result in a *copy*. Closes [#481](https://github.com/Rdatatable/data.table/issues/481). 
+  33.  `DT[, list(list(.)), by=.]` and `DT[, col := list(list(.)), by=.]` returns correct results in R >=3.1.0 as well. The bug was due to recent (welcoming) changes in R v3.1.0 where `list(.)` does not result in a *copy*. Closes [#481](https://github.com/Rdatatable/data.table/issues/481). Also thanks to KrishnaPG for filing [#728](https://github.com/Rdatatable/data.table/issues/728).
 
   34.  `dcast.data.table` handles `fun.aggregate` argument properly when called from within a function that accepts `fun.aggregate` argument and passes to `dcast.data.table()`. Closes [#713](https://github.com/Rdatatable/data.table/issues/713). Thanks to mathematicalcoffee for reporting [here](http://stackoverflow.com/q/24542976/559784) on SO.
 

inst/tests/tests.Rraw

@@ -4838,11 +4838,15 @@ test(1340.18, setorderv(copy(DT), "x", na.last=NA), error="na.last must be logic
 
 # bug #481 - DT[, list(list(.)), by=.] on R v3.1.0
 set.seed(1L)
+f <- function(x) list(x)
 DT <- data.table(x=sample(3,10,TRUE), y=as.numeric(sample(10)))
 test(1341.1, DT[, list(list(y)), by=x], data.table(x=unique(DT$x), V1=list(c(3,5,9), c(2,6,4,1), c(10,7,8))))
 test(1341.2, DT[, list(list(.I)), by=x], data.table(x=unique(DT$x), V1=list(c(1,5,10), c(2,3,8,9), c(4,6,7))))
-f <- function(x) list(x)
 test(1341.3, DT[, list(f(y)), by=x], data.table(x=unique(DT$x), V1=list(c(3,5,9), c(2,6,4,1), c(10,7,8))))
+# test for list(list(.)) with :=
+test(1341.4, copy(DT)[, z := list(list(y)), by=x], copy(DT)[, z := list(list(copy(y))), by=x])
+test(1341.5, copy(DT)[, z := list(list(.I)), by=x], copy(DT)[, z := list(list(copy(.I))), by=x])
+test(1341.6, copy(DT)[, z := list(f(y)), by=x], copy(DT)[, z := list(f(copy(y))), by=x])
 
 # test regression on over-allocation (selfref) on unique() which uses new subsetDT()
 bla <- data.table(x=c(1,1,2,2), y=c(1,1,1,1))

src/dogroups.c

@@ -287,7 +287,29 @@ SEXP dogroups(SEXP dt, SEXP dtcols, SEXP groups, SEXP grpcols, SEXP jiscols, SEX
                 // fix for #4990 - `:=` did not issue recycling warning during "by" operation.
                 if (vlen<grpn && vlen>0 && grpn%vlen != 0) 
                     warning("Supplied %d items to be assigned to group %d of size %d in column '%s' (recycled leaving remainder of %d items).",vlen,i+1,grpn,CHAR(STRING_ELT(dtnames,INTEGER(lhs)[j]-1)),grpn%vlen);
+                // fix for issues/481 for := case
+                // missed it in commit: https://github.com/Rdatatable/data.table/commit/86276f48798491d328caa72f6ebcce4d51649440
+                // see that link (or scroll down for the non := version) for comments
+                #if defined(R_VERSION) && R_VERSION >= R_Version(3, 1, 0)
+                named=0;
+                if (isNewList(RHS) && NAMED(RHS) != 2) {
+                    dupcol = VECTOR_ELT(RHS, 0);
+                    named  = NAMED(dupcol);
+                    while(isNewList(dupcol)) {
+                        if (named == 2) break;
+                        else {
+                            dupcol = VECTOR_ELT(dupcol, 0);
+                            named = NAMED(dupcol);
+                        }
+                    }
+                    if (named == 2) RHS = PROTECT(duplicate(RHS));
+                }
+                memrecycle(target, order, INTEGER(starts)[i]-1, grpn, RHS);
+                if (named == 2) UNPROTECT(1);
+                #else
                 memrecycle(target, order, INTEGER(starts)[i]-1, grpn, RHS);
+                #endif
+
                 // fixes bug #2531. Got to set the class back. See comment below for explanation. This is the new fix. Works great!
                 // Also fix for #5437 (bug due to regression in 1.9.2+)
                 copyMostAttrib(RHS, target);  // not names, otherwise test 778 would fail